Statistical Design, a Powerful Tool for Optimizing Biosurfactant Production: A Review
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paper_title: Biosurfactants Produced by Marine Microorganisms with Therapeutic Applications

paper_content:

Marine microorganisms possess unique metabolic and physiological features and are an important source of new biomolecules, such as biosurfactants. Some of these surface-active compounds synthesized by marine microorganisms exhibit antimicrobial, anti-adhesive and anti-biofilm activity against a broad spectrum of human pathogens (including multi-drug resistant pathogens), and could be used instead of existing drugs to treat infections caused by them. In other cases, these biosurfactants show anti-cancer activity, which could be envisaged as an alternative to conventional therapies. However, marine biosurfactants have not been widely explored, mainly due to the difficulties associated with the isolation and growth of their producing microorganisms. Culture-independent techniques (metagenomics) constitute a promising approach to study the genetic resources of otherwise inaccessible marine microorganisms without the requirement of culturing them, and can contribute to the discovery of novel biosurfactants with significant biological activities. This paper reviews the most relevant biosurfactants produced by marine microorganisms with potential therapeutic applications and discusses future perspectives and opportunities to discover novel molecules from marine environments.
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paper_title: Response surface optimization of biosurfactant produced by Pseudomonas aeruginosa MA01 isolated from spoiled apples.

paper_content:

A potent biosurfactant-producing bacterial strain isolated from spoiled apples was identified by 16S rRNA as Pseudomonas aeruginosa MA01. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages of lipid (66%, w/w) and carbohydrate (32%, w/w). The surface tension of pure water decreased gradually with increasing biosurfactant concentration to 32.5 mN m(-1) with critical micelle concentration (CMC) value of 10.1 mg L(-1). The Fourier transform infrared spectrum of extracted biosurfactant confirmed the glycolipid nature of this natural product. Response surface methodology (RSM) was employed to optimize the biosynthesis medium for the production of MA01 biosurfactant. Nineteen carbon sources and 11 nitrogen sources were examined, with soybean oil and sodium nitrate being the most effective carbon and nitrogen sources on biosurfactant production, respectively. Among the organic nitrogen sources examined, yeast extract was necessary as a complementary nitrogen source for high production yield. Biosurfactant production at the optimum value of fermentation processing factor (15.68 g/L) was 29.5% higher than the biosurfactant concentration obtained before the RSM optimization (12.1 g/L). A central composite design algorithm was used to optimize the levels of key medium components, and it was concluded that two stages of optimization using RSM could increase biosurfactant production by 1.46 times, as compared to the values obtained before optimization.
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paper_title: Critical review on biosurfactant analysis, purification and characterization using rhamnolipid as a model biosurfactant

paper_content:

Surfactants are one of the most versatile group of chemicals used in various industrial processes. Their market is competitive, and manufacturers will have to expand surfactant production in ecofriendly and cost effective manner. Increasing interest in biosurfactants led to an intense research for environment friendly and cost-efficient production of biosurfactant. Structural diversity and functional properties of biosurfactants make them an attractive group of compounds for potential use in wide variety of industrial, environmental and biotechnological applications. Screening methods make task easier to obtain potential biosurfactant producing microorganisms. Variety of purification and analytical methods are available for biosurfactant structural characterization. This review aims to compile information on types and properties of biosurfactant, microbial screening methods as well as biosynthesis, extraction, purification and structural characterization of biosurfactant using rhamnolipid as a model biosurfactant. It also describes factors affecting rhamnolipid production. It gives an overview of oil recovery using biosurfactant from Pseudomonas aeruginosa.
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paper_title: Microbial biosurfactants production, applications and future potential

paper_content:

Microorganisms synthesise a wide range of surface-active compounds (SAC), generally called biosurfactants. These compounds are mainly classified according to their molecular weight, physico-chemical properties and mode of action. The low-molecular-weight SACs or biosurfactants reduce the surface tension at the air/water interfaces and the interfacial tension at oil/water interfaces, whereas the high-molecular-weight SACs, also called bioemulsifiers, are more effective in stabilising oil-in-water emulsions. Biosurfactants are attracting much interest due to their potential advantages over their synthetic counterparts in many fields spanning environmental, food, biomedical, and other industrial applications. Their large-scale application and production, however, are currently limited by the high cost of production and by limited understanding of their interactions with cells and with the abiotic environment. In this paper, we review the current knowledge and the latest advances in biosurfactant applications and the biotechnological strategies being developed for improving production processes and future potential.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Biosurfactants in cosmetic formulations: trends and challenges

paper_content:

AbstractCosmetic products play an essential role in everyone’s life. People everyday use a large variety of cosmetic products such as soap, shampoo, toothpaste, deodorant, skin care, perfume, make-up, among others. The cosmetic industry encompasses several environmental, social and economic impacts that are being addressed through the search for more efficient manufacturing techniques, the reduction of waste and emissions and the promotion of personal hygiene, contributing to an improvement of public health and at the same time providing employment opportunities. The current trend among consumers is the pursuit for natural ingredients in cosmetic products, as many of these products exhibit equal, better or additional benefits in comparison with the chemical-based products. In this sense, biosurfactants are natural compounds with great potential in the formulation of cosmetic products given by their biodegradability and impact in health. Indeed, many of these biosurfactants could exhibit a “prebiotic” char...
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paper_title: Stimulation of rhamnolipid biosurfactants production in Pseudomonas aeruginosa AK6U by organosulfur compounds provided as sulfur sources

paper_content:

A Pseudomonas aeruginosa AK6U strain produced rhamnolipid biosurfactants to variable extents when grown on MgSO4 or organosulfur compounds as sulfur sources and glucose as a carbon source. Organosulfur cultures produced much higher biosurfactants amounts compared to the MgSO4 cultures. The surface tension of the growth medium was reduced from 72 mN/m to 54 and 30 mN/m in cultures containing MgSO4 and 4,6-dimethyldibenzothiophene (4,6-DM-DBT), respectively. AK6U cultures produced different rhamnolipid congener profiles depending on the provided sulfur source. The dibenzothiophene (DBT) culture produced more diverse and a higher number of rhamnolipid congeners as compared to the DBT-sulfone and MgSO4 cultures. The number of mono-rhamnolipid congeners in the DBT culture was also higher than that detected in the DBT-sulfone and MgSO4 cultures. Di-rhamnolipids dominated the congener profiles in all the analyzed cultures. The sulfur source can have a profound impact on the quality and quantity of the produced biosurfactants.
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Evaluation of the effect of nutrient ratios on biosurfactant production by Serratia marcescens using a Box-Behnken design.

paper_content:

The strain SmSA, identified as Serratia marcescens and known as a biosurfactant producer, was isolated from hydrocarbon contaminated soil from Veracruz, México. The interactions among the C/N, C/Mg and C/Fe ratios have not been examined for this microorganism. In this work was evaluated the effect of these nutrients at three levels using a mineral medium with glucose as the carbon source. A Box-Behnken experimental design was utilised to maximise biosurfactant production, which was assessed by oil spreading and surface tension tests. The treatment with C/N=5, C/Fe=26,000 and C/Mg=30 showed the best result since the surface tension was reduced to 30 mN m(-1). The multiple regression and response surface analyses indicated that the interaction between C/N and C/Mg had the utmost effect on the reduction of surface tension and biosurfactant production. The conditions of the best treatment were used to scale up biosurfactant production in a 3L bioreactor giving a yield of 4.1 gL(-1) of pure biosurfactant. It was found that the biosurfactant was mainly produced in the exponential phase and decreased the surface tension to 31 mN m(-1). The contact between the biosurfactant with heavy oil (15° API) increased its displacement from 9.3 to 18 cm.
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paper_title: Use of response surface optimization for the production of biosurfactant from Rhodococcus spp. MTCC 2574.

paper_content:

The production of biosurfactant from Rhodococcus spp. MTCC 2574 was effectively enhanced by response surface methodology (RSM). Rhodococcus spp. MTCC 2574 was selected through screening of seven different Rhodococcus strains. The preliminary screening experiments (one-factor at a time) suggested that carbon source: mannitol, nitrogen source: yeast extract and meat peptone and inducer: n-hexadecane are the critical medium components. The concentrations of these four media components were optimized by using central composite rotatable design (CCRD) of RSM. The adequately high R2 value (0.947) and F score 19.11 indicated the statistical significance of the model. The optimum medium composition for biosurfactant production was found to contain mannitol (1.6 g/L), yeast extract (6.92 g/L), meat peptone (19.65 g/L), n-hexadecane (63.8 g/L). The crude biosurfactant was obtained from methyl tert-butyl ether extraction. The yield of biosurfactant before and after optimization was 3.2 g/L of and 10.9 g/L, respectively. Thus, RSM has increased the yield of biosurfactant to 3.4-fold. The crude biosurfactant decreased the surface tension of water from 72 mN/m to 30.8 mN/m (at 120 mg L(-1)) and achieved a critical micelle concentration (CMC) value of 120 mg L(-1).
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paper_title: Genetic regulations of the biosynthesis of microbial surfactants: an overview.

paper_content:

Microbial biosurfactants are surface active metabolites synthesized by microbes growing on a variety of substrates. In spite of having great potential for commercial, therapeutic and environmental applications, industrial level production has not been realized for their low yields and productivities. One vital factor determining their biosynthesis is the genetic makeup of the producer organisms. Studies on molecular genetics and biochemistry of the synthesis of several biosurfactants have revealed the operons, the enzymes and the metabolic pathways required for their extracellular production. Surfactin, a cyclic lipopeptide biosurfactant is a potent antimicrobial agent and is produced as a result of non-ribosomal biosynthesis catalyzed by a large multienzyme peptide synthetase complex called the surfactin synthetase. Pathways for the synthesis of other lipopeptides such as iturin, lichenysin and arthrofactin are also mediated by similar enzyme complexes. These non-ribosomal peptide synthetases (NRPSs) responsible for lipopeptide biosynthesis display a high degree of structural similarity among themselves even from distant microbial species. Plasmid-encoded- rhlA, B, R and I genes of rhl quorum sensing system are required for production of glycolipid biosurfactants by Pseudomonas species. Molecular genetics of biosynthesis of alasan and emulsan by Acinetobacter species and of the fungal biosurfactants such as mannosylerythritol lipids (MEL) and hydrophobins have been deciphered. However, limited genetic information is available about biosynthesis of other biosurfactants such as viscosin, amphisin and putisolvin produced by some strains of Pseudomonas species. Understanding of the genetic regulatory mechanisms would help to develop metabolically engineered hyper-producing strains with better product characteristics and acquired capability of utilizing cheap agro-industrial wastes as substrates. This article thus provides an overview of the role and importance of molecular genetics and gene regulation mechanisms behind the biosynthesis of various microbial surfactants of commercial importance.
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paper_title: Production and characterization of rhamnolipid biosurfactant from waste frying coconut oil using a novel Pseudomonas aeruginosa D

paper_content:

Aim ::: ::: To improve biosurfactant production economics by the utilization of potential low-cost materials. ::: ::: ::: ::: Methods and Results ::: ::: In an attempt to utilize cost-effective carbon sources in the fermentative production of biosurfactants, various pure and waste frying oils were screened by a standard biosurfactant producing strain. Considering the regional significance, easy availability and the economical advantages, waste frying coconut oil was selected as the substrate for further studies. On isolation of more competent strains that could use waste frying coconut oil efficiently as a carbon source, six bacterial strains were isolated on cetyltrimethyl ammonium bromide–methylene blue agar plate, from a soil sample collected from the premises of a coconut oil mill. Among these, Pseudomonas aeruginosa D was selected as the potential producer of rhamnolipid. Spectrophotometric method, TLC, methylene blue active substance assay, drop collapse technique, surface tension measurement by Du Nouy ring method and emulsifying test confirmed the rhamnolipid producing ability of the selected strain and various process parameters were optimized for the production of maximum amount of biosurfactant. Rhamnolipid components purified and separated by ethyl acetate extraction, preparative silica gel column chromatography, HPLC and TLC were characterized by fast atom bombardment mass spectrometry as a mixture of dirhamnolipids and monorhamnolipids. The rhamnolipid homologues detected were Rha-Rha-C10-C10, Rha-C12-C10 and Rha-C10-C8/Rha-C8-C10. ::: ::: ::: ::: Conclusion ::: ::: These results indicated the possibility of waste frying coconut oil to be used as a very effective alternate substrate for the economic production of rhamnolipid by a newly isolated Ps. aeruginosa D. ::: ::: ::: ::: Significance and Impact of the Study ::: ::: Results of this study throws light on the alternate use of already used cooking oil as high-energy source for producing a high value product like rhamnolipid. This would provide options for the food industry other than the recycling and reuse of waste frying oils in cooking and also furthering the value of oil nuts.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Media optimization for biosurfactant production by Rhodococcus erythropolis MTCC 2794: artificial intelligence versus a statistical approach

paper_content:

This paper entails a comprehensive study on production of a biosurfactant from Rhodococcus erythropolis MTCC 2794. Two optimization techniques--(1) artificial neural network (ANN) coupled with genetic algorithm (GA) and (2) response surface methodology (RSM)--were used for media optimization in order to enhance the biosurfactant yield by Rhodococcus erythropolis MTCC 2794. ANN and RSM models were developed, incorporating the quantity of four medium components (sucrose, yeast extract, meat peptone, and toluene) as independent input variables and biosurfactant yield [calculated in terms of percent emulsification index (% EI(24))] as output variable. ANN-GA and RSM were compared for their predictive and generalization ability using a separate data set of 16 experiments, for which the average quadratic errors were approximately 3 and approximately 6%, respectively. ANN-GA was found to be more accurate and consistent in predicting optimized conditions and maximum yield than RSM. For the ANN-GA model, the values of correlation coefficient and average quadratic error were approximately 0.99 and approximately 3%, respectively. It was also shown that ANN-based models could be used accurately for sensitivity analysis. ANN-GA-optimized media gave about a 3.5-fold enhancement in biosurfactant yield.
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Effects of Various Nutritional Supplements on Biosurfactant Production by a Strain of Bacillus subtilis at 45°C

paper_content:

Effects of various factors on growth and biosurfactant production by Bacillus subtilis MTCC 2423 were studied. Sucrose (2%) and potassium nitrate (0.3%) were the best carbon and nitrogen sources. The addition of various metal supplements (magnesium, calcium, iron, and trace elements) greatly affected growth and biosurfactant production. The effect of the metal cations, used together, is greater than when they are used individually. The biosurfactant production increased considerably (almost double) by addition of metal supplements. Very high concentrations of metal supplements, however, inhibited biosurfactant production. Amino acids such as aspartic acid, asparagine, glutamic acid, valine, and lysine increased the final yield of biosurfactant by about 60%. The organism could produce biosurfactant at 45°C and within the pH range of 4.5–10.5. The biosurfactant was thermostable and pH stable (from 4.0 to 12.0). The capability of the organism to produce biosurfactant under thermophilic, alkaliphilic, and halophilic conditions makes it a suitable candidate for field applications. Infrared, nuclear magnetic resonance, and mass spectroscopy studies showed the surfactant to be identical to surfactin.
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paper_title: Isolation of biosurfactant producers, optimization and properties of biosurfactant produced by Acinetobacter sp. from petroleum-contaminated soil

paper_content:

Aims: To screen and identify biosurfactant producers from petroleum-contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. ::: Methods and Results: We successfully isolated three biosurfactant producers from petroleum-contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57AE5% increase of the growth-associated biosurfactant production ::: by Acinetobacter sp. YC-X 2 with an optimized medium: beef extract ::: 3AE12 g l)1 ; peptone 20AE87 g l)1 ; NaCl 1AE04 g l)1 ; and n-hexadecane 1AE86 g l)1. Biosurfactant produced by Acinetobacter sp. YC-X 2 retained its properties during exposure to a wide range of pH values (5–11), high temperatures (up to 121C) and high salinities [up to 18% (w⁄ v) Na+ and Ca2+], which was more sensitive to Ca2+ than Na+ . ::: Conclusions: Two novel biosurfactant producers were isolated from petroleumcontaminated soil. Biosurfactant from Acinetobacter sp. YC-X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM.
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paper_title: Stimulation of rhamnolipid biosurfactants production in Pseudomonas aeruginosa AK6U by organosulfur compounds provided as sulfur sources

paper_content:

A Pseudomonas aeruginosa AK6U strain produced rhamnolipid biosurfactants to variable extents when grown on MgSO4 or organosulfur compounds as sulfur sources and glucose as a carbon source. Organosulfur cultures produced much higher biosurfactants amounts compared to the MgSO4 cultures. The surface tension of the growth medium was reduced from 72 mN/m to 54 and 30 mN/m in cultures containing MgSO4 and 4,6-dimethyldibenzothiophene (4,6-DM-DBT), respectively. AK6U cultures produced different rhamnolipid congener profiles depending on the provided sulfur source. The dibenzothiophene (DBT) culture produced more diverse and a higher number of rhamnolipid congeners as compared to the DBT-sulfone and MgSO4 cultures. The number of mono-rhamnolipid congeners in the DBT culture was also higher than that detected in the DBT-sulfone and MgSO4 cultures. Di-rhamnolipids dominated the congener profiles in all the analyzed cultures. The sulfur source can have a profound impact on the quality and quantity of the produced biosurfactants.
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paper_title: Statistical optimization of medium components for the production of biosurfactant by Bacillus licheniformis K51.

paper_content:

The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were H3PO4, CaCl2, H3BO3, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose, 1.1; NaNO3, 4.4; MgSO4 x 7H2O, 0.8; KCl, 0.4; CaCl2, 0.27; H3PO4, 1.0 ml/l; and trace elements (mg/l): H3BO3, 0.25; CuSO4, 0.6; MnSO4, 2.2; Na2MoO4, 0.5; ZnSO4, 6.0; FeSO4, 8.0; CoCl2, 1.0; and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from 10x to 105x, which is ten times higher than the non-optimized rich medium.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Using Taguchi experimental design methods to optimize trace element composition for enhanced surfactin production by Bacillus subtilis ATCC 21332

paper_content:

Abstract In this work, optimizing trace element composition was attempted as a primary strategy to improve surfactin production from Bacillus subtilis ATCC 21332. Statistical experimental design (Taguchi method) was applied for the purpose of identifying optimal trace element composition in the medium. Of the five trace elements examined, Mg 2+ , K + , Mn 2+ , and Fe 2+ were found to be more significant factors affecting surfactin production by the B. subtilis strain. In the absence of Mg 2+ or K + , surfactin yield decreased to 0.4 g/l, which was only 25% of the value obtained from the control run. When Mn 2+ and Fe 2+ were both absent, the production yield also dropped to ca. 0.6 g/l, approximately one-third of the control value. However, when only one of the two metal ions (Fe 2+ or Mn 2+ ) was missing, the B. subtilis ATCC 21332 strain was able to remain over 80% of original surfactin productivity, suggesting that some interactive correlations among the selected metal ions may involve. Taguchi method was thus applied to reveal the interactive effects of Mg 2+ , K + , Mn 2+ , Fe 2+ on surfactin production. The results show that interaction of Mg 2+ and K + reached significant level. By further optimizing Mg 2+ and K + concentrations in the medium, the surfactin production was boosted to 3.34 g/l, which nearly doubled the yield obtained from the original control.
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paper_title: Stimulation of rhamnolipid biosurfactants production in Pseudomonas aeruginosa AK6U by organosulfur compounds provided as sulfur sources

paper_content:

A Pseudomonas aeruginosa AK6U strain produced rhamnolipid biosurfactants to variable extents when grown on MgSO4 or organosulfur compounds as sulfur sources and glucose as a carbon source. Organosulfur cultures produced much higher biosurfactants amounts compared to the MgSO4 cultures. The surface tension of the growth medium was reduced from 72 mN/m to 54 and 30 mN/m in cultures containing MgSO4 and 4,6-dimethyldibenzothiophene (4,6-DM-DBT), respectively. AK6U cultures produced different rhamnolipid congener profiles depending on the provided sulfur source. The dibenzothiophene (DBT) culture produced more diverse and a higher number of rhamnolipid congeners as compared to the DBT-sulfone and MgSO4 cultures. The number of mono-rhamnolipid congeners in the DBT culture was also higher than that detected in the DBT-sulfone and MgSO4 cultures. Di-rhamnolipids dominated the congener profiles in all the analyzed cultures. The sulfur source can have a profound impact on the quality and quantity of the produced biosurfactants.
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paper_title: Response surface optimization of biosurfactant produced by Pseudomonas aeruginosa MA01 isolated from spoiled apples.

paper_content:

A potent biosurfactant-producing bacterial strain isolated from spoiled apples was identified by 16S rRNA as Pseudomonas aeruginosa MA01. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages of lipid (66%, w/w) and carbohydrate (32%, w/w). The surface tension of pure water decreased gradually with increasing biosurfactant concentration to 32.5 mN m(-1) with critical micelle concentration (CMC) value of 10.1 mg L(-1). The Fourier transform infrared spectrum of extracted biosurfactant confirmed the glycolipid nature of this natural product. Response surface methodology (RSM) was employed to optimize the biosynthesis medium for the production of MA01 biosurfactant. Nineteen carbon sources and 11 nitrogen sources were examined, with soybean oil and sodium nitrate being the most effective carbon and nitrogen sources on biosurfactant production, respectively. Among the organic nitrogen sources examined, yeast extract was necessary as a complementary nitrogen source for high production yield. Biosurfactant production at the optimum value of fermentation processing factor (15.68 g/L) was 29.5% higher than the biosurfactant concentration obtained before the RSM optimization (12.1 g/L). A central composite design algorithm was used to optimize the levels of key medium components, and it was concluded that two stages of optimization using RSM could increase biosurfactant production by 1.46 times, as compared to the values obtained before optimization.
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paper_title: Optimization of cultural conditions for biosurfactant production from Candida lipolytica

paper_content:

Abstract The maximisation of the production of metabolites of industrial interest from fermentative processes, such as biosurfactants, requires standardisation of the medium and the cultivation conditions. In this sense, experiments were conducted to maximise the production of the biosurfactant from Candida lipolytica UCP0988 cultivated on 5% animal fat and 2.5% corn steep liquor using a 23 full factorial design. The effects and interactions of the agitation speed (200, 300 and 400 rpm), the variables aeration (0, 1 and 2 vvm) and time of cultivation (48, 96 and 144 h) on the surface tension, yield and biomass were evaluated. The results showed that the variable time of cultivation had positive influence on the production of biosurfactant, while the increase of the variables aeration and agitation showed a negative effect. These results indicate that the biosurfactant has a strong potential to be applied as a clean-up of oil spills at sea and on shorelines.
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paper_title: Isolation of biosurfactant producers, optimization and properties of biosurfactant produced by Acinetobacter sp. from petroleum-contaminated soil

paper_content:

Aims: To screen and identify biosurfactant producers from petroleum-contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. ::: Methods and Results: We successfully isolated three biosurfactant producers from petroleum-contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57AE5% increase of the growth-associated biosurfactant production ::: by Acinetobacter sp. YC-X 2 with an optimized medium: beef extract ::: 3AE12 g l)1 ; peptone 20AE87 g l)1 ; NaCl 1AE04 g l)1 ; and n-hexadecane 1AE86 g l)1. Biosurfactant produced by Acinetobacter sp. YC-X 2 retained its properties during exposure to a wide range of pH values (5–11), high temperatures (up to 121C) and high salinities [up to 18% (w⁄ v) Na+ and Ca2+], which was more sensitive to Ca2+ than Na+ . ::: Conclusions: Two novel biosurfactant producers were isolated from petroleumcontaminated soil. Biosurfactant from Acinetobacter sp. YC-X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM.
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paper_title: Enhancing biosurfactant production from an indigenous strain of Bacillus mycoides by optimizing the growth conditions using a response surface methodology

paper_content:

Abstract In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34 mN/m. Compositional analysis of the produced biosurfactant has been carried out by thin layer chromatography (TLC) and FT-IR. The biosurfactant produced by the isolate was characterized as lipopeptide derivative. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology (RSM). The factor selected for optimization of growth conditions were pH, temperature, glucose and salinity concentrations. The empirical model developed through RSM in terms of effective operational factors mentioned above was found to be adequate to describe the biosurfactant production. Through the analysis, glucose and temperature were found to be the most significant factors, whereas pH and salinity had less effect within the ranges investigated. A maximum reduction in surface tension was obtained under the optimal conditions of 16.55 g/l glucose concentration, 39.03 °C, 55.05 g/l total salt concentration and medium pH 7.37.
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paper_title: Experimental Design and Data Analysis for Biologists

paper_content:

1. Introduction 2. Estimation 3. Hypothesis testing 4. Graphical exploration of data 5. Correlation and regression 6. Multiple regression and correlation 7. Design and power analysis 8. Comparing groups or treatments - analysis of variance 9. Multifactor analysis of variance 10. Randomized blocks and simple repeated measures: unreplicated two-factor designs 11. Split plot and repeated measures designs: partly nested anovas 12. Analysis of covariance 13. Generalized linear models and logistic regression 14. Analyzing frequencies 15. Introduction to multivariate analyses 16. Multivariate analysis of variance and discriminant analysis 17. Principal components and correspondence analysis 18. Multidimensional scaling and cluster analysis 19. Presentation of results.
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paper_title: Statistical optimization of medium components for the production of biosurfactant by Bacillus licheniformis K51.

paper_content:

The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were H3PO4, CaCl2, H3BO3, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose, 1.1; NaNO3, 4.4; MgSO4 x 7H2O, 0.8; KCl, 0.4; CaCl2, 0.27; H3PO4, 1.0 ml/l; and trace elements (mg/l): H3BO3, 0.25; CuSO4, 0.6; MnSO4, 2.2; Na2MoO4, 0.5; ZnSO4, 6.0; FeSO4, 8.0; CoCl2, 1.0; and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from 10x to 105x, which is ten times higher than the non-optimized rich medium.
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paper_title: Mixed Experimental Methodologies to Optimize Biosurfactant Production Conditions of Pseudomonas Aeruginosa

paper_content:

In order to reduce production cost of Pseudomonas aeruginosa T1, which has the ability of producing the biosurfactant when using crude oil as the sole carbon source, Three experimental methodologies (Plackett-Burman design (PBD), steepest ascent design (SAD), Central composite rotatable design (CCRD)) were applied to optimize the medium ingredients of the strain. In the verification experiment, the surface tension (ST) of strain T1 fermentation decreased from 29.93mN/m to 27.08mN/m after medium optimization.
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paper_title: Optimization of biosurfactant production by Streptomyces isolated from Egyptian arid soil using Plackett–Burman design

paper_content:

Surfactants are amphipathic molecules which reduce surface tension, widely used in pharmaceutical, cosmetic and food industries. The current study aimed to isolate Streptomyces species from Egyptian arid soil, efficient in biosurfactant production. Fifty isolates of Streptomyces were obtained from arid soil in Egypt. Primary screening, using lipase, drop collapse, parafilm M and haemolysis tests, showed 37 isolates (74%) having biosurfactant activity. Secondary screening resulted in 17 isolates based on their activities using emulsification index method. Isolate 5S was selected as the most efficient in biosurfactant production, having emulsification index equal to 31.74%. Plackett–Burman design was adopted to evaluate the factors affecting biosurfactant production. Among the tested nine variables of starch nitrate medium, treated molasses, peptone, Tween 80, incubation period and inoculum size were identified as significant factors affecting biosurfactant production. Cultivation of isolate 5S in the optimized medium elevated biosurfactant production to 42.68% (according to emulsification index) from 31.74%, obtained in un-optimized medium.
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paper_title: Biosurfactants in cosmetic formulations: trends and challenges

paper_content:

AbstractCosmetic products play an essential role in everyone’s life. People everyday use a large variety of cosmetic products such as soap, shampoo, toothpaste, deodorant, skin care, perfume, make-up, among others. The cosmetic industry encompasses several environmental, social and economic impacts that are being addressed through the search for more efficient manufacturing techniques, the reduction of waste and emissions and the promotion of personal hygiene, contributing to an improvement of public health and at the same time providing employment opportunities. The current trend among consumers is the pursuit for natural ingredients in cosmetic products, as many of these products exhibit equal, better or additional benefits in comparison with the chemical-based products. In this sense, biosurfactants are natural compounds with great potential in the formulation of cosmetic products given by their biodegradability and impact in health. Indeed, many of these biosurfactants could exhibit a “prebiotic” char...
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paper_title: Optimizing carbon/nitrogen ratio for biosurfactant production by a Bacillus subtilis strain

paper_content:

A Bacillus subtilis strain isolated from contaminated soil from a refinery has been screened for biosurfactant production in crystal sugar (sucrose) with different nitrogen sources (NaNO3, (NH4)2SO4, urea, and residual brewery yeast). The highest reduction in surface tension was achieved with a 48-h fermentation of crystal sugar and ammonium nitrate. Optimization of carbon/nitrogen ratio (3, 9, and 15) and agitation rate (50, 150, and 250 rpm) for biosurfactant production was carried out using complete factorial design and response surface analysis. The condition of C/N 3 and 250 rpm allowed the maximum increase in surface activity of biosurfactant. A suitable model has been developed, having presented great accordance experimental data. Preliminary characterization of the bioproduct suggested it to be a lipopeptide with some isomers differing from those of a commercial surfactin.
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paper_title: Factorial Design to Optimize Biosurfactant Production by Yarrowia lipolytica

paper_content:

In order to improve biosurfactant production by Yarrowia lipolytica IMUFRJ 50682, a factorial design was carried out. A full factorial design was used to investigate the effects of nitrogen sources (urea, ammonium sulfate, yeast extract, and peptone) on maximum variation of surface tension (ST) and emulsification index (EI). The best results (67.7% of EI and 20.9 mN of ST) were obtained in a medium composed of 10 g of ammonium sulfate and 0.5 g of yeast extract. Then, the effects of carbon sources (glycerol, hexadecane, olive oil, and glucose) were evaluated. The most favorable medium for biosurfactant production was composed of both glucose (4% w/v) and glycerol (2% w/v), which provided an EI of 81.3% and a ST of 19.5 mN . The experimental design optimization enhanced EI by 110.7% and ST by 108.1% in relation to the standard process.
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paper_title: Optimization of cultural conditions for biosurfactant production from Candida lipolytica

paper_content:

Abstract The maximisation of the production of metabolites of industrial interest from fermentative processes, such as biosurfactants, requires standardisation of the medium and the cultivation conditions. In this sense, experiments were conducted to maximise the production of the biosurfactant from Candida lipolytica UCP0988 cultivated on 5% animal fat and 2.5% corn steep liquor using a 23 full factorial design. The effects and interactions of the agitation speed (200, 300 and 400 rpm), the variables aeration (0, 1 and 2 vvm) and time of cultivation (48, 96 and 144 h) on the surface tension, yield and biomass were evaluated. The results showed that the variable time of cultivation had positive influence on the production of biosurfactant, while the increase of the variables aeration and agitation showed a negative effect. These results indicate that the biosurfactant has a strong potential to be applied as a clean-up of oil spills at sea and on shorelines.
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paper_title: Using Taguchi experimental design methods to optimize trace element composition for enhanced surfactin production by Bacillus subtilis ATCC 21332

paper_content:

Abstract In this work, optimizing trace element composition was attempted as a primary strategy to improve surfactin production from Bacillus subtilis ATCC 21332. Statistical experimental design (Taguchi method) was applied for the purpose of identifying optimal trace element composition in the medium. Of the five trace elements examined, Mg 2+ , K + , Mn 2+ , and Fe 2+ were found to be more significant factors affecting surfactin production by the B. subtilis strain. In the absence of Mg 2+ or K + , surfactin yield decreased to 0.4 g/l, which was only 25% of the value obtained from the control run. When Mn 2+ and Fe 2+ were both absent, the production yield also dropped to ca. 0.6 g/l, approximately one-third of the control value. However, when only one of the two metal ions (Fe 2+ or Mn 2+ ) was missing, the B. subtilis ATCC 21332 strain was able to remain over 80% of original surfactin productivity, suggesting that some interactive correlations among the selected metal ions may involve. Taguchi method was thus applied to reveal the interactive effects of Mg 2+ , K + , Mn 2+ , Fe 2+ on surfactin production. The results show that interaction of Mg 2+ and K + reached significant level. By further optimizing Mg 2+ and K + concentrations in the medium, the surfactin production was boosted to 3.34 g/l, which nearly doubled the yield obtained from the original control.
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paper_title: Optimization of Bacillus subtilis SPB1 Biosurfactant Production Under Solid-state Fermentation Using By-products of a Traditional Olive Mill Factory

paper_content:

Abstract Bacillus subtilis SPB1 is known to produce a highly effective biosurfactant that belongs to the class of lipopeptides. This biosurfactant has shown relevant properties that could be efficiently applied in various domains. However, high production and purification costs limit the use of B. subtilis SPB1 in high-volume applications. The present work aimed to promote an economical production of this lipopeptide biosurfactant. Statistical experimental designs and response surface methodology were employed to optimize the concentrations of agro-industrial residues, inoculum size and humidity for B. subtilis SPB1 biosurfactant production under solid-state fermentation. The best production yield was approximately 30.67 mg of crude lipopeptide biosurfactant per gram of solid material. This yield was obtained using a solid substrate ratio of 1.5, a moisture content of 90% and an inoculum size (OD600) of 0.08. These data support the utilization of a mixture of 6 g of olive leaf residue flour and 4 g of olive cake flour with a 10g total weight of the solid substrate. A mixture of two by-products of a traditional olive mill factory was demonstrated to be a suitable substrate for biosurfactant biosynthesis, providing enhanced bacterial growth and leading to a strong improvement in the yield of tensioactive lipopeptide production.
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region

paper_content:

Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.
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paper_title: Optimization of biosurfactant production by Bacillus brevis using response surface methodology

paper_content:

The present study aims to evaluate and validate a statistical model for maximizing biosurfactant productivity by Bacillus brevis using response surface methodology. In this respect, twenty bacterial isolates were screened for biosurfactant production using hemolytic activity, oil spreading technique, and emulsification index (E24). The most potent biosurfactant-producing bacterium (B. brevis) was used for construction of the statistical response surface model. The optimum conditions for biosurfactant production by B. brevis were: 33 °C incubation temperature at pH 8 for 10 days incubation period and 8.5 g/L glucose concentration as a sole carbon source. The produced biosurfactant (BS) (73%) exhibited foaming activity, thermal stability in the range 30-80 °C for 30 min., pH stability, from 4 to 9 and antimicrobial activity against (Escherichia coli). The BS gave a good potential application as an emulsifier.
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paper_title: Isolation of biosurfactant producers, optimization and properties of biosurfactant produced by Acinetobacter sp. from petroleum-contaminated soil

paper_content:

Aims: To screen and identify biosurfactant producers from petroleum-contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. ::: Methods and Results: We successfully isolated three biosurfactant producers from petroleum-contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57AE5% increase of the growth-associated biosurfactant production ::: by Acinetobacter sp. YC-X 2 with an optimized medium: beef extract ::: 3AE12 g l)1 ; peptone 20AE87 g l)1 ; NaCl 1AE04 g l)1 ; and n-hexadecane 1AE86 g l)1. Biosurfactant produced by Acinetobacter sp. YC-X 2 retained its properties during exposure to a wide range of pH values (5–11), high temperatures (up to 121C) and high salinities [up to 18% (w⁄ v) Na+ and Ca2+], which was more sensitive to Ca2+ than Na+ . ::: Conclusions: Two novel biosurfactant producers were isolated from petroleumcontaminated soil. Biosurfactant from Acinetobacter sp. YC-X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM.
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paper_title: Enhancing biosurfactant production from an indigenous strain of Bacillus mycoides by optimizing the growth conditions using a response surface methodology

paper_content:

Abstract In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34 mN/m. Compositional analysis of the produced biosurfactant has been carried out by thin layer chromatography (TLC) and FT-IR. The biosurfactant produced by the isolate was characterized as lipopeptide derivative. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology (RSM). The factor selected for optimization of growth conditions were pH, temperature, glucose and salinity concentrations. The empirical model developed through RSM in terms of effective operational factors mentioned above was found to be adequate to describe the biosurfactant production. Through the analysis, glucose and temperature were found to be the most significant factors, whereas pH and salinity had less effect within the ranges investigated. A maximum reduction in surface tension was obtained under the optimal conditions of 16.55 g/l glucose concentration, 39.03 °C, 55.05 g/l total salt concentration and medium pH 7.37.
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paper_title: Evaluation of the effect of nutrient ratios on biosurfactant production by Serratia marcescens using a Box-Behnken design.

paper_content:

The strain SmSA, identified as Serratia marcescens and known as a biosurfactant producer, was isolated from hydrocarbon contaminated soil from Veracruz, México. The interactions among the C/N, C/Mg and C/Fe ratios have not been examined for this microorganism. In this work was evaluated the effect of these nutrients at three levels using a mineral medium with glucose as the carbon source. A Box-Behnken experimental design was utilised to maximise biosurfactant production, which was assessed by oil spreading and surface tension tests. The treatment with C/N=5, C/Fe=26,000 and C/Mg=30 showed the best result since the surface tension was reduced to 30 mN m(-1). The multiple regression and response surface analyses indicated that the interaction between C/N and C/Mg had the utmost effect on the reduction of surface tension and biosurfactant production. The conditions of the best treatment were used to scale up biosurfactant production in a 3L bioreactor giving a yield of 4.1 gL(-1) of pure biosurfactant. It was found that the biosurfactant was mainly produced in the exponential phase and decreased the surface tension to 31 mN m(-1). The contact between the biosurfactant with heavy oil (15° API) increased its displacement from 9.3 to 18 cm.
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paper_title: Study of the synergistic effects of salinity, pH, and temperature on the surface-active properties of biosurfactants produced by Lactobacillus pentosus.

paper_content:

Many studies have investigated the effects of pH, temperature, and salinity on the surface-active properties of various surfactants, although in most cases the variables have been studied separately, without considering the effects of any interactions between them. In the present study, a Box-Behnken factorial design was applied to study the effects of pH, temperature, and salinity on the surface-active properties of a biosurfactant produced by Lactobacillus pentosus. The data obtained enabled development of a second-order model describing the interrelationships between operational and experimental variables, by equations including linear, interaction, and quadratic terms. The variable that had the greatest effect on the surface-active properties of the biosurfactant was pH. Moreover, at pH 3-5.5, decreases in salinity and temperature acted synergistically, reducing the surface tension of the biosurfactant; at pH 8, the same effect was observed with increasing salinity and temperature.
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paper_title: Response surface methodology (Box-Behnken) to improve a liquid media formulation to produce biosurfactant and phenanthrene removal by Pseudomonas putida

paper_content:

A culture medium formulation was established using a Box-Behnken experimental design aimed at enhancing biosurfactant production and phenanthrene removal by Pseudomonas putida CB-100. The independent variables selected (+, 0, −, levels) were: glucose (9.1, 13.6, and 18.2 g/l), NH4Cl (0.5, 0.75, and 1.0 g/l), and yeast extract (0.005, 0.0075, and 0.01 g/l), with 200 mg/l phenanthrene at 37°C, shaken at 150 rpm, at pH 7, for 5 days. Analyses of results by one-way analysis of variance showed that biosurfactant production was improved by the glucose–ammonium chloride interaction at high values (p < 0.004). Phenanthrene removal was enhanced by the ammonium chloride-yeast extract interaction at low and high values, respectively (p < 0.02). The highest phenanthrene removal (82.4%) was observed in formulation 11, which had a C:N ratio of 5:1 and a C:P ratio of 10:1. In addition, 47.5 mN/m surface tension, 20% emulsion capacity, and 23.5 mg/l biosurfactant production were obtained. With this medium, we followed the kinetic growth of P. putida for 118 h, the culture conditions were the same as those used in the experimental design. At 46 h, we obtained 57.8% phenanthrene removal and 27 mg/l biosurfactant production. The critical micelle concentration of the biosurfactant was 430 mg/l. The biosurfactant produced by P. putida was characterized as a rhamnolipid type.
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paper_title: Optimization of Inocula Conditions for Enhanced Biosurfactant Production by Bacillus subtilis SPB1, in Submerged Culture, Using Box–Behnken Design

paper_content:

The inoculum age and density can influence considerably the production yield and cost of the fermentation process. Some literature studies report the use of two-stage inocula to enhance metabolite production. In the present study, optimization studies were done in order to define the best inocula conditions supporting a maximum biosurfactant production by Bacillus subtilis SPB1. Hence, by adjusting the levels of the two-stage inocula strategy, lipopeptide production was effectively enhanced to almost 3.4 g/l as estimated gravimetrically. The new defined parameters were as follows; a first inoculum age of 23 h followed by a second inoculum age and size of 4 h and 0.01, respectively. Thereby, we note an improved production as compared to the production yield described under non-optimized inocula conditions reported in our previous work.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Optimization and characterization of a new lipopeptide biosurfactant produced by marine Brevibacterium aureum MSA13 in solid state culture

paper_content:

The biosurfactant production of a marine actinobacterium Brevibacterium aureum MSA13 was optimized using industrial and agro-industrial solid waste residues as substrates in solid state culture (SSC). Based on the optimization experiments, the biosurfactant production by MSA13 was increased to threefold over the original isolate under SSC conditions with pre-treated molasses as substrate and olive oil, acrylamide, FeCl3 and inoculums size as critical control factors. The strain B. aureum MSA13 produced a new lipopeptide biosurfactant with a hydrophobic moiety of octadecanoic acid methyl ester and a peptide part predicted as a short sequence of four amino acids including pro-leu-gly-gly. The biosurfactant produced by the marine actinobacterium MSA13 can be used for the microbially enhanced oil recovery processes in the marine environments.
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paper_title: Kinetic study and modeling of biosurfactant production using Bacillus sp.

paper_content:

Background: Surfactant is one of the most important raw materials used in various industrial fields, such as emulsifiers, corrosion inhibitors, foaming agent and detergent products. However, the commercial surfactant production is still costly and its demand is steadily increasing. This study aims to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through a fermentation process. It also included the investigation of effect of initial glucose concentration and the ratio of carbon to nitrogen. Results: The biosurfactant was produced in the range of 1-2.46 g/L at initial glucose concentrations of 10-70 g/L. The optimum condition was achieved at a carbon to nitrogen ratio of 12.4 with the decrease in surface tension up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation was proposed to predict the cell mass and biosurfactant production as the goodness of fitting was obtained. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ ::: table.MsoNormalTable ::: {mso-style-name:"Tabla normal"; ::: mso-tstyle-rowband-size:0; ::: mso-tstyle-colband-size:0; ::: mso-style-noshow:yes; ::: mso-style-priority:99; ::: mso-style-parent:""; ::: mso-padding-alt:0cm 5.4pt 0cm 5.4pt; ::: mso-para-margin:0cm; ::: mso-para-margin-bottom:.0001pt; ::: mso-pagination:widow-orphan; ::: font-size:10.0pt; ::: font-family:"Times New Roman",serif; ::: mso-ansi-language:EN-GB; ::: mso-fareast-language:EN-GB;}
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paper_title: The use of Gompertz models in growth analyses, and new Gompertz-model approach: An addition to the Unified-Richards family

paper_content:

The Gompertz model is well known and widely used in many aspects of biology. It has been frequently used to describe the growth of animals and plants, as well as the number or volume of bacteria and cancer cells. Numerous parametrisations and re-parametrisations of varying usefulness are found in the literature, whereof the Gompertz-Laird is one of the more commonly used. Here, we review, present, and discuss the many re-parametrisations and some parameterisations of the Gompertz model, which we divide into Ti (type I)- and W0 (type II)-forms. In the W0-form a starting-point parameter, meaning birth or hatching value (W0), replaces the inflection-time parameter (Ti). We also propose new "unified" versions (U-versions) of both the traditional Ti -form and a simplified W0-form. In these, the growth-rate constant represents the relative growth rate instead of merely an unspecified growth coefficient. We also present U-versions where the growth-rate parameters return absolute growth rate (instead of relative). The new U-Gompertz models are special cases of the Unified-Richards (U-Richards) model and thus belong to the Richards family of U-models. As U-models, they have a set of parameters, which are comparable across models in the family, without conversion equations. The improvements are simple, and may seem trivial, but are of great importance to those who study organismal growth, as the two new U-Gompertz forms give easy and fast access to all shape parameters needed for describing most types of growth following the shape of the Gompertz model.
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paper_title: Statistical optimization of medium components for the production of biosurfactant by Bacillus licheniformis K51.

paper_content:

The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were H3PO4, CaCl2, H3BO3, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose, 1.1; NaNO3, 4.4; MgSO4 x 7H2O, 0.8; KCl, 0.4; CaCl2, 0.27; H3PO4, 1.0 ml/l; and trace elements (mg/l): H3BO3, 0.25; CuSO4, 0.6; MnSO4, 2.2; Na2MoO4, 0.5; ZnSO4, 6.0; FeSO4, 8.0; CoCl2, 1.0; and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from 10x to 105x, which is ten times higher than the non-optimized rich medium.
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paper_title: Statistical Methodologies for the Optimization of Lipase and Biosurfactant by Ochrobactrum intermedium Strain MZV101 in an Identical Medium for Detergent Applications

paper_content:

The Plackett–Burman design and the Box–Behnken design, statistical methodologies, were employed for the optimization lipase and biosurfactant production by Ochrobactrum intermedium strain MZV101 in an identical broth medium for detergent applications. Environmental factor pH determined to be most mutual significant variables on production. A high concentration of molasses at high temperature and pH has a negative effect on lipase and biosurfactant production by O. intermedium strain MZV101. The chosen mathematical method of medium optimization was sufficient for improving the industrial production of lipase and biosurfactant by bacteria, which were respectively increased 3.46- and 1.89-fold. The duration of maximum production became 24 h shorter, so it was fast and cost-saving. In conclusion, lipase and biosurfactant production by O. intermedium strain MZV101 in an identical culture medium at pH 10.5–11 and 50–60 °C, with 1 g/L of molasses, seemed to be economical, fast, and effective for the enhancement of yield percentage for use in detergent applications.
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paper_title: Mixed Experimental Methodologies to Optimize Biosurfactant Production Conditions of Pseudomonas Aeruginosa

paper_content:

In order to reduce production cost of Pseudomonas aeruginosa T1, which has the ability of producing the biosurfactant when using crude oil as the sole carbon source, Three experimental methodologies (Plackett-Burman design (PBD), steepest ascent design (SAD), Central composite rotatable design (CCRD)) were applied to optimize the medium ingredients of the strain. In the verification experiment, the surface tension (ST) of strain T1 fermentation decreased from 29.93mN/m to 27.08mN/m after medium optimization.
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paper_title: Use of response surface optimization for the production of biosurfactant from Rhodococcus spp. MTCC 2574.

paper_content:

The production of biosurfactant from Rhodococcus spp. MTCC 2574 was effectively enhanced by response surface methodology (RSM). Rhodococcus spp. MTCC 2574 was selected through screening of seven different Rhodococcus strains. The preliminary screening experiments (one-factor at a time) suggested that carbon source: mannitol, nitrogen source: yeast extract and meat peptone and inducer: n-hexadecane are the critical medium components. The concentrations of these four media components were optimized by using central composite rotatable design (CCRD) of RSM. The adequately high R2 value (0.947) and F score 19.11 indicated the statistical significance of the model. The optimum medium composition for biosurfactant production was found to contain mannitol (1.6 g/L), yeast extract (6.92 g/L), meat peptone (19.65 g/L), n-hexadecane (63.8 g/L). The crude biosurfactant was obtained from methyl tert-butyl ether extraction. The yield of biosurfactant before and after optimization was 3.2 g/L of and 10.9 g/L, respectively. Thus, RSM has increased the yield of biosurfactant to 3.4-fold. The crude biosurfactant decreased the surface tension of water from 72 mN/m to 30.8 mN/m (at 120 mg L(-1)) and achieved a critical micelle concentration (CMC) value of 120 mg L(-1).
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paper_title: Response surface optimization of biosurfactant produced by Pseudomonas aeruginosa MA01 isolated from spoiled apples.

paper_content:

A potent biosurfactant-producing bacterial strain isolated from spoiled apples was identified by 16S rRNA as Pseudomonas aeruginosa MA01. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages of lipid (66%, w/w) and carbohydrate (32%, w/w). The surface tension of pure water decreased gradually with increasing biosurfactant concentration to 32.5 mN m(-1) with critical micelle concentration (CMC) value of 10.1 mg L(-1). The Fourier transform infrared spectrum of extracted biosurfactant confirmed the glycolipid nature of this natural product. Response surface methodology (RSM) was employed to optimize the biosynthesis medium for the production of MA01 biosurfactant. Nineteen carbon sources and 11 nitrogen sources were examined, with soybean oil and sodium nitrate being the most effective carbon and nitrogen sources on biosurfactant production, respectively. Among the organic nitrogen sources examined, yeast extract was necessary as a complementary nitrogen source for high production yield. Biosurfactant production at the optimum value of fermentation processing factor (15.68 g/L) was 29.5% higher than the biosurfactant concentration obtained before the RSM optimization (12.1 g/L). A central composite design algorithm was used to optimize the levels of key medium components, and it was concluded that two stages of optimization using RSM could increase biosurfactant production by 1.46 times, as compared to the values obtained before optimization.
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paper_title: Enhanced di-rhamnolipid production with an indigenous isolate Pseudomonas aeruginosa J16

paper_content:

Abstract A newly isolated indigenous strain Pseudomonas aeruginosa J16 was able to produce a glycolipid biosurfactant (i.e., rhamnolipid). Analyses with 13 C NMR and mass spectrometry show that the biosurfactant consisted mainly of mono-rhamnolipid (RL1) and di-rhamnolipid (RL2). Since RL2 possesses higher surface activity than RLl and is of better applicability and commercial benefits, the present work attempted to enhance the production of RL2 over RL1 in P. aeruginosa J16 from the perspective of medium improvement. The results show that the abundance and composition of RL1 and RL2 varied with the type of carbon and nitrogen sources used. When glycerol and NH 4 Cl were used as the carbon and nitrogen sources, respectively, an RL2 production of 448.3 mg/L was obtained with a volumetric productivity of 4.67 mg/(L h) and a RL2/RL1 ratio of 4.22 (by mass). Replacing NH 4 Cl by (NH 4 ) 2 SO 4 , the RL2 concentration and volumetric productivity were improved to 2121 mg/L and 22.1 mg/(L h), respectively, with the RL2/RL1 ratio of 3.0. To further enhance RL2 production, statistical experimental design methodology was applied to optimize the culture medium composition favoring RL2 synthesis. Three key parameters (glycerol, (NH 4 ) 2 SO 4 , and MgSO 4 ·7H 2 O) were selected by two-level factorial design. Response surface methodology was then used to identify the optimal composition of the three key parameters, giving an optimal concentration of 0.38 M, 33.3 mM, and 577 μM for glycerol, (NH 4 ) 2 SO 4 , and MgSO 4 ·7H 2 O, respectively. With this optimal medium, the RL2 production could be markedly elevated to a maximum concentration of 3190 mg/L and a volumetric productivity of 44.3 mg/(L h), while the RL2/RL1 ratio maintained nearly constant at a value of 3.0.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Media optimization for biosurfactant production by Rhodococcus erythropolis MTCC 2794: artificial intelligence versus a statistical approach

paper_content:

This paper entails a comprehensive study on production of a biosurfactant from Rhodococcus erythropolis MTCC 2794. Two optimization techniques--(1) artificial neural network (ANN) coupled with genetic algorithm (GA) and (2) response surface methodology (RSM)--were used for media optimization in order to enhance the biosurfactant yield by Rhodococcus erythropolis MTCC 2794. ANN and RSM models were developed, incorporating the quantity of four medium components (sucrose, yeast extract, meat peptone, and toluene) as independent input variables and biosurfactant yield [calculated in terms of percent emulsification index (% EI(24))] as output variable. ANN-GA and RSM were compared for their predictive and generalization ability using a separate data set of 16 experiments, for which the average quadratic errors were approximately 3 and approximately 6%, respectively. ANN-GA was found to be more accurate and consistent in predicting optimized conditions and maximum yield than RSM. For the ANN-GA model, the values of correlation coefficient and average quadratic error were approximately 0.99 and approximately 3%, respectively. It was also shown that ANN-based models could be used accurately for sensitivity analysis. ANN-GA-optimized media gave about a 3.5-fold enhancement in biosurfactant yield.
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paper_title: Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids byPseudomonas aeruginosa AT10

paper_content:

Pseudomonas aeruginosa AT10 produced a mixture of surface-active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2 4 full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO 3 ), the phosphate content (K 2 HPO 4 /KH 2 PO 4 2:1) and the iron content (FeSO 4 7H 2 O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm -3 DCW, when the medium contained 50 g dm -3 carbon source, 9 g dm -3 NaNO 3 , 7 g dm 3 phosphate and 13.7 mg dm -3 FeSO 4 7H 2 O. The maximum concentration of rhamnolipid, 18.7 g dm 3 , was attained in medium that contained 50 g dm -3 carbon source, 4.6 g dm 3 NaNO 3 , 1 g dm 3 phosphate and 7.4 mg dm 3 FeSO 4 7H 2 O.
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paper_title: Response surface optimization of the medium components for the production of biosurfactants by probiotic bacteria

paper_content:

Optimization of the medium for biosurfactants production by probiotic bacteria (Lactococcus lactis 53 and Streptococcus thermophilus A) was carried out using response surface methodology. Both biosurfactants were proved to be growth-associated, thus the desired response selected for the optimization was the biomass concentration. The selected factors based on MRS medium for L. lactis 53 growth were peptone, meat extract, yeast extract, lactose, ammonium citrate and KH2PO4. For S. thermophilus A based on the M17 medium, the selected factors were peptone, meat extract, yeast extract, lactose, soya peptone and sodium glycerophosphate. The optimum MRS composition was found to be 38.6 g/l peptone, 43.0 g/l lactose, 10 g/l. meat extract, 5.g/l yeast extract, 1.08 g/l Tween-80(E), 2 g/l KH2PO4, 2 g/l CH3COONa, 2 g/l ammonium citrate, 0.2 g/l MgSO(4)center dot 7H(2)O and 0.05 g/l MnSO(4)center dot 4H(2)O. The optimized medium allowed a mass of produced biosurfactant (milligram per gram cell dry weight) 1.6 times higher compared to MRS standard medium. The optimum medium composition for growing S. thermophilus A consists of 5.0 g/l peptone, 5.7 g/l lactose, 5.0 g/l meat extract, 2.5 g/l yeast extract, 5.0 g/l soya peptone, 26.4 g/l sodium glycerophosphate, 0.5 g/l ascorbic acid and 0.25 g/l MgSO(4)center dot 7H(2)O. With the optimization procedure a biosurfactant mass recovery 2.1 times higher was achieved. The application of response surface methodology resulted in an enhancement in biosurfactants production. (C) 2005 Elsevier Ltd. All rights reserved.
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paper_title: Statistical approach to optimize production of biosurfactant by Pseudomonas aeruginosa 2297

paper_content:

The main objective of this paper is to optimize biosurfactant production by Pseudomonas aeruginosa 2297 with statistical approaches. Biosurfactant production from P. aeruginosa 2297 was carried out with different carbon sources, and maximum yield was achieved with sawdust followed by groundnut husk and glycerol. The produced biosurfactant has showed active emulsification and surface-active properties. From the kinetic growth modeling, the specific growth rate was calculated on sawdust and it was 1.12 day−1. The maximum estimated value of product yield on biomass growth (Yp/x) was 1.02 g/g. The important medium components identified by the Plackett–Burman method were sawdust and glycerol along with culture parameter pH. Box–Behnken response surface methodology was applied to optimize biosurfactant production. The obtained experimental result concludes that Box–Behnken designs are very effective statistical tools to improve biosurfactant production. These results may be useful to develop a high efficient production process of biosurfactant. In addition, this type of kinetic modeling approach may constitute a useful tool to design and scaling-up of bioreactors for the production of biosurfactant.
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paper_title: Optimization of rhamnolipid biosurfactant production by mangrove sediment bacterium Pseudomonas aeruginosa KVD-HR42 using response surface methodology

paper_content:

Abstract Rhamnolipid biosurfactant production by a novel Pseudomonas aeruginosa strain KVD-HR42 was optimized with statistical approaches. The produced biosurfactant showed surface active properties with stable emulsification activities. Based on the results of Plackett–Burman design, first-order polynomial model was developed and the following significant variables were determined viz., Karanja oil, sodium nitrate and pH. Response surface methodology experimental design was performed by Box–Behnken design to study the concentration of each component. The response plots resulted in the following optimized conditions; Karanja oil (23.85 g/L) sodium nitrate (9.17 g/L) and pH (7.8) which yielded an average biosurfactant production of 5.90±2.1 g/L at 48 h, and 37 °C temperature. The statistical approach resulted in enhanced biosurfactant production. The biosurfactant showed excellent emulsion forming capabilities and could reduce the surface tension to 30.14 mN/m at a CMC value of 100 mg/L. The biosurfactant was found to be stable at extreme conditions of temperature, pH and NaCl concentrations. Additionally surface active nature of the crude biosurfactant was demonstrated using oil displacement assay with a clearance zone of 19.26±0.23 cm 2 . Our results signify that the biosurfactant has a great industrial potential as a cleansing agent at adverse environmental conditions and provide better alternative to synthetic surfactants.
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paper_title: Improved production, purification, and characterization of biosurfactants produced by Serratia marcescens SM3 and its isogenic SMRG‐5 strain

paper_content:

In this study, the biosurfactants (Bs) production of two Serratia marcescens strains (SM3 and its isogenic SMRG-5 strain) was improved and the tenso-active agents were purified and characterized. A 23 factorial design was used to evaluate the effect of nitrogen and carbon sources on the surface tension (ST) reduction and emulsion index (EI24 ) of the produced Bs. Optimum Bs production by SM3 was achieved at high concentrations of carbon and nitrogen, reducing ST to 26.5 ± 0.28 dynes/cm, with an EI24 of 79.9 ± 0.2%. Meanwhile, the best results for SMRG-5 were obtained at low concentrations, reducing the ST to 25.2 ± 0.2 dynes/cm, with an EI24 of 89.7 ± 0.28%. The optimal conditions for Bs production were scaled up in a 2-L reactor, yielding 4.8 and 5.2 g/L for SM3 and SMRG-5, respectively. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed the presence of two different lipopeptides (hidrofobic fractions: octadecanoic and hexadecanoic acid for SM3 and SMRG5, respectively). Both strains were capable of benzo [a] pyrene removal (59% after 72 H of culture).
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Estimation of biosurfactant yield produced by Klebseilla sp. FKOD36 bacteria using artificial neural network approach

paper_content:

Abstract Environmental and medium parameters estimation is an essential step in Bioprocess engineering. In the present study, artificial neural network (ANN) was employed in estimation of biosurfactants yield from bacterial strain Klebseilla sp. FKOD36, surface tension reduction as well emulsification index. The data obtained from experimental design were used in modelling and optimization of ANN method. Temperature, pH value, incubation period, carbon, nitrogen and hydrocarbon sources were used as input of ANN model independently in the prediction of biosurfactants yield, surface tension reduction and emulsification index. Using the optimized values of critical input elements of ANN, the experimental values of biosurfactant yield, emulsification index and surface tension showed close agreement with the model estimate. The most efficient ANN model assessment was 0.030 g/l for actual value 0.038 g/l of biosurfactant yield, 31.67% for actual value 31.68% of emulsification index, and 21.6 dyne/cm for actual value 21.5 dyne/cm of surface tension respectively.
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paper_title: Media optimization for biosurfactant production by Rhodococcus erythropolis MTCC 2794: artificial intelligence versus a statistical approach

paper_content:

This paper entails a comprehensive study on production of a biosurfactant from Rhodococcus erythropolis MTCC 2794. Two optimization techniques--(1) artificial neural network (ANN) coupled with genetic algorithm (GA) and (2) response surface methodology (RSM)--were used for media optimization in order to enhance the biosurfactant yield by Rhodococcus erythropolis MTCC 2794. ANN and RSM models were developed, incorporating the quantity of four medium components (sucrose, yeast extract, meat peptone, and toluene) as independent input variables and biosurfactant yield [calculated in terms of percent emulsification index (% EI(24))] as output variable. ANN-GA and RSM were compared for their predictive and generalization ability using a separate data set of 16 experiments, for which the average quadratic errors were approximately 3 and approximately 6%, respectively. ANN-GA was found to be more accurate and consistent in predicting optimized conditions and maximum yield than RSM. For the ANN-GA model, the values of correlation coefficient and average quadratic error were approximately 0.99 and approximately 3%, respectively. It was also shown that ANN-based models could be used accurately for sensitivity analysis. ANN-GA-optimized media gave about a 3.5-fold enhancement in biosurfactant yield.
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paper_title: Artificial neural network modeling and genetic algorithm based medium optimization for the improved production of marine biosurfactant.

paper_content:

A nonlinear model describing the relationship between the biosurfactant concentration as a process output and the critical medium components as the independent variables was developed by artificial neural network modeling. The model was optimized for the maximum biosurfactant production by using genetic algorithm. Based on a single-factor-at-a-time optimization strategy, the critical medium components were found to be glucose, urea, SrCl(2) and MgSO(4). The experimental results obtained from a statistical experimental design were used for the modeling and optimization by linking an artificial neural network (ANN) model with genetic algorithm (GA) in MATLAB. Using the optimized concentration of critical elements, the biosurfactant yield showed close agreement with the model prediction. An enhancement in biosurfactant production by approximately 70% was achieved by this optimization procedure.
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paper_title: Pleurotus ostreatus laccase recovery from residual compost using aqueous two‐phase systems

paper_content:

BACKGROUND: Multiple aqueous two‐phase systems (ATPS) were evaluated for the partial purification of laccase from a crude aqueous extract. The laccase extract was obtained from residual compost, generated from the production of the edible mushroom Pleurotus ostreatus. A total of 59 ATPS were evaluated; 16 systems using poly (ethylene glycol) (PEG) and phosphates, 20 systems using UCON (ethylene oxide/propylene oxide copolymer) and different salts, and 23 polymer–polymer systems (Ficoll, Dextran and PEG). RESULTS: Protein partitioning was not achieved with the PEG–phosphate systems. ATPS composed of UCON and salts presented great potential for laccase recovery, with up to 95.12 ± 5.27, 96.05 ± 4.99 and 98.31 ± 3.58% recovery, and purification factors of 5.02, 4.14 and 9.97 for the UCON‐NaH₂PO₄ , UCON‐NaSO₄, and UCON‐(NH₄)₂SO₄ systems, respectively. The PEG 10 000/Dextran 10 000 and the PEG 10 000/Dextran 100 000 polymer–polymer systems proved to have potential, presenting purification factors as high as 5.78 and 6.56, respectively. CONCLUSION: The laccase analyzed in this study had a molecular weight of approximately 30 kDa, and thus, is the smallest laccase yet to be reported for P. ostreatus. ATPS represent an attractive alternative for the efficient recovery of laccase from residual compost generated after P. ostreatus production. © 2016 Society of Chemical Industry
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paper_title: Critical review on biosurfactant analysis, purification and characterization using rhamnolipid as a model biosurfactant

paper_content:

Surfactants are one of the most versatile group of chemicals used in various industrial processes. Their market is competitive, and manufacturers will have to expand surfactant production in ecofriendly and cost effective manner. Increasing interest in biosurfactants led to an intense research for environment friendly and cost-efficient production of biosurfactant. Structural diversity and functional properties of biosurfactants make them an attractive group of compounds for potential use in wide variety of industrial, environmental and biotechnological applications. Screening methods make task easier to obtain potential biosurfactant producing microorganisms. Variety of purification and analytical methods are available for biosurfactant structural characterization. This review aims to compile information on types and properties of biosurfactant, microbial screening methods as well as biosynthesis, extraction, purification and structural characterization of biosurfactant using rhamnolipid as a model biosurfactant. It also describes factors affecting rhamnolipid production. It gives an overview of oil recovery using biosurfactant from Pseudomonas aeruginosa.
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paper_title: Comparative study of the production of rhamnolipid biosurfactants by B. thailandensis E264 and P. aeruginosa ATCC 9027 using foam fractionation

paper_content:

Biosurfactants are surface-active agents that are produced by a variety of microorganisms including yeasts, filamentous fungi and bacteria. In this work, we report on the ability of Pseudomonas aeruginosa ATCC 9027 and Burkholderia thailandensis E264 to produce rhamnolipids via a 10-L bioreactor and their recovery through foam fractionation studies in a continuous stripping mode. The recovery of Rha-C10-C10 (mono-rhamnolipids) produced by P. aeruginosa ATCC 9027 increased (from 6% to 96%), whilst the enrichment decreased (from 2.9 to 1.2) with the increasing airflow rate. These results are consistent with foam fractionation of a single surfactant system with stable foam. The recovery and enrichment of Rha-Rha-C14-C14 (di-rhamnolipids) produced by B. thailandensis E264 (and an unknown molecule) in a single-component system were found to display different characteristics. Both recovery and enrichment were found to decrease with the airflow rate. It is postulated that a competitive adsorption process could occur between the smaller molecule identified by electrospray ionisation–mass spectrometry (ESI–MS) and Rha-Rha-C14-C14.
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paper_title: Biosurfactants: Production and Applications

paper_content:

Great emphasis has recently been given to the environmental impacts caused by chemical surfactants due to their toxicity and difficulty in being degraded in the environment [1]. Increasing environmental concerns, the advance in biotechnology and the emergence of more stringent laws have led to biosurfactants being a potential alternative to the chemical surfac‐ tants available on the market [2, 3]. Although biosurfactants have promising use in bioreme‐ diation processes, their industrial scale production is currently difficult due to high rawmaterial costs, high processing costs and low manufacturing output [3]. As a result, the current research challenges are to increase the yield and to reduce the cost of raw materials [4].
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paper_title: Optimization of extraction conditions and fatty acid characterization ofLactobacillus pentosuscell-bound biosurfactant/bioemulsifier

paper_content:

BACKGROUND ::: ::: There is currently much interest in the use of natural biosurfactants and bioemulsifiers, mainly in the cosmetic, pharmaceutical and food industries. However, there are no studies on the optimization of the extraction conditions of cell-bound biosurfactants. In this work, a biosurfactant with emulsifier properties was extracted from Lactobacillus pentosus cells, under different extraction conditions, and characterized. ::: ::: ::: ::: RESULTS ::: ::: During extraction, the most influential independent variable, concerning the emulsifying capacity of biosurfactant, was the operation time, followed by temperature and salt concentration. Biosurfactant from L. pentosus was evaluated by Fourier transform infrared spectroscopy and the composition of fatty acids was analyzed by gas chromatography–mass spectrometry. The hydrophobic chain of the biosurfactant from L. pentosus comprises 548 g kg−1 linoelaidic acid (C18:2), 221 g kg−1 oleic or elaidic acid (C18:1), 136 g kg−1 palmitic acid (C16) and 95 g kg−1 stearic acid (C18). In addition, emulsions of water and rosemary oil were stabilized with a biosurfactant produced by L. pentosus and compared with emulsions stabilized with polysorbate 20. ::: ::: ::: ::: CONCLUSION ::: ::: The optimum extraction conditions of biosurfactant were achieved at 45 °C at 120 min and using 9 g kg−1 of salt. In all the assays biosurfactant from L. pentosus yielded more stable emulsions and higher emulsion volumes than polysorbate 20. © 2014 Society of Chemical Industry
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paper_title: In situ downstream strategies for cost-effective bio/surfactant recovery

paper_content:

Since 60–80% of total costs of production are usually associated with downstream collection, separation and purification processes, it has become advantageous to investigate how to replace traditional methods with efficient and cost-effective alternative techniques for recovery and purification of biosurfactants. In the traditional techniques, large volumes of organic solvents are usually used increasing production cost and the overall environmental burden. In addition, traditional production and separation methods typically carried out in batch cultures reduce biosurfactant yields due to product inhibition and lower biosurfactants activity as a result of interaction with the organic solvents used. However, some in situ recovery methods that allow continuous separation of bioproducts from culture broth leading to an improvement in yield production and fermentation efficiency. For biosurfactants commercialization, enhancement of product capacity of the separation methods and the rate of product removal is critical. Recently, interest in the integration of separation methods with production step as rapid and efficient techniques has been increasing. This review focuses on the technology gains and potentials for the most common methods used in in situ product removal (ISPR): Foam fractionation and Ultrafiltration, especially used to recover and purify two well-known biosurfactants: glycolipids (rhamnolipids) and lipopeptides (surfactins). ::: ::: This article is protected by copyright. All rights reserved
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Title: Statistical Design, a Powerful Tool for Optimizing Biosurfactant Production: A Review

Section 1: Introduction
Description 1: Introduce the significance of biosurfactants (Bs), their industrial applications, and the challenges associated with their production and commercialization.

Section 2: Factors Affecting Bs Production
Description 2: Discuss the various factors that affect biosurfactant production, including carbon and nitrogen sources, trace elements, and physicochemical parameters such as pH, temperature, and shaking.

Section 3: Strains, Bs Classification and Metabolism
Description 3: Review the different microorganisms known for producing biosurfactants, the types of biosurfactants they produce, and their metabolic pathways.

Section 4: Effect of Carbon and Nitrogen Sources
Description 4: Explore the impact of different carbon and nitrogen sources on biosurfactant production and the importance of selecting appropriate nutrient sources.

Section 5: The Effect of Trace Elements on Bs Production
Description 5: Explain the role of trace elements in biosurfactant production and their metabolic interactions with the producing microorganisms.

Section 6: Physicochemical Factors Affecting Bs Production: The Effect of pH, Temperature, and Shaking
Description 6: Analyze how pH, temperature, and shaking influence biosurfactant production and optimize these parameters for different microorganisms.

Section 7: Statistical Design, an Efficient Tool for Bs Production Optimization
Description 7: Discuss the benefits of using statistical designs for optimizing biosurfactant production, including factorial designs and Response Surface Methodologies (RSM).

Section 8: Two-Level Factorial Designs
Description 8: Describe the two-level factorial design approach and its application in biosurfactant production optimization.

Section 9: Plackett-Burman 
Description 9: Review the Plackett-Burman design and its efficiency in screening numerous factors affecting biosurfactant production without accounting for interactions.

Section 10: Other Two-Level Factorial Designs
Description 10: Provide examples of other two-level factorial designs used in optimizing biosurfactant production, illustrating their effectiveness.

Section 11: Response Surface Methodology (RSM)
Description 11: Explain Response Surface Methodology and its usefulness in dealing with multifactor experiments for biosurfactant optimization.

Section 12: Central Composite Design
Description 12: Detail the Central Composite Design (CCD) method and provide examples of its application in enhancing biosurfactant production.

Section 13: Box-Behnken
Description 13: Outline the Box-Behnken design's structure and provide case studies where it has been used to optimize biosurfactant production.

Section 14: Modified Gompertz Equation
Description 14: Introduce the Modified Gompertz Equation and its novel application in predicting cell mass and biosurfactant production.

Section 15: Mixed Strategies
Description 15: Discuss the use of combined statistical methodologies for a comprehensive optimization of biosurfactant production.

Section 16: Analytical Hierarchy Process (AHP)
Description 16: Explain the Analytical Hierarchy Process (AHP) and its application in identifying important factors influencing biosurfactant production.

Section 17: Artificial Neural Network
Description 17: Explore the use of Artificial Neural Network (ANN) models for optimizing biosurfactant production and handling complex non-linear biological interactions.

Section 18: Improving Downstream Processes
Description 18: Discuss the importance of optimizing downstream processes such as recovery and purification to make biosurfactant production more cost-effective.

Section 19: Concluding Remarks
Description 19: Summarize the advantages of using statistical designs in enhancing biosurfactant production and outline the potential future directions in this field.

Section 20: Conflicts of Interest
Description 20: Disclose any potential conflicts of interest related to the authors of the paper.