3: Environmental Microbiology

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A critters gotta do what a critters gotta do


Unicellular and multicellular organisms formerly classified as plants, occurring in fresh or salt water or moist ground, that have chlorophyll and other pigments but lack true stems, roots, and leaves.
Dates to the Precambrian period
They have a wide range of reproductive strategy, from asexual cell division to sexual reproduction

Harmful Algae

Harmful algal blooms may cause harm through the production of toxins or by their accumulated biomass


Fungi break down organic material and continue to cycle of nutrients through the ecosystem.

Harmful Fungi



Major players in the cycles of carbon, nitrogen and sulfur. They can remain dormant for an extended period of time, making them easily spreadable.
They lack the membrane-bound nuclei of eukaryotes.

Aerobic bacteria

Thrive in the presence of oxygen

Anaerobic bacteria

Cannot tolerate gaseous oxygen

Facultative anaerobes



The breakdown of dead organisms, and the release of nutrients back into the environment

Why is the nitrogen cycle necessary?

Plant rely on nitrogen from the soil for their health and growth. They cannot acquire it from the gaseous nitrogen in the atmosphere. The primary way nitrogen becomes available to them is through nitrogen fixation by bacteria


Viruses depend on the cells that they infect to reproduce. When found outside of the cells, viruses exist as a protein coat or capsid. The capsid encloses either DNA or RNA which codes for the virus elements
When it comes into contact with a host cell, a virus can insert its genetic material into its host. An infected cell then produces more viral proteins and gentical material instead of its usual products

The Four Main Requirements for Bacterial Growth are

2. Moisture
3. Warmth
4. Time

How do bacteria like their environment?

They like neutral conditions (PH of 7) and will not grow in foods with a PH below 4.5

Bacteria that grow in low temperatures (below 20 degrees Celsius) are called psychrophiles
Bacteria that grow at high temperatures (above 45 degrees Celsius) are called thermophiles

Why do bacteria like nitrates?

They're better than day rates.


What are the optimal growth temperatures for microbes?

Most pathogens like warmth and are known as mesophiles. They will grow at temperatures between 5 degrees and 63 degrees celcius (aka the danger zone Que scary music). Mesophiles have an optimum temperature growth of 37 degrees celcius
Most bacteria will become inactive under five degrees celcius, but Listeria has to ruin it for everyone by growing very slowly below 5 degrees

What is the recommended temperature and time for killing pathogens during cooking?

70 degrees Celsius for 2 minutes

Why did the bacteria fail his math test?

He thought multiplication was the same as division!

eh!? good one.

Coliform Bacteria

Coliforms are not a single type of bacteria, but a grouping of bacteria that includes many strains. They live in soil or vegetation and in the GI tract of animals. Coliforms enter water supplies from the direct disposal of waste into streams or lakes or from runoff

What is the standard by which microbial contamination is measured?

Total coliform

Nosocomial Infections

Infection acquired in a hospital.

Problematic because people in hospitls are already in a poor state of health. If a patient is treated with immunosuppresants, antacid treatment, or antimicrobal treatment, the may be vulnerable for nosocomial infections

How to control nosocomial infections

1. Wash yo hands, fool
2. Cleaning, disinfection, and sterilization
3. Personal Protective Equipment
4. Antimicrobial surfaces


Disinfection refers to the use of liquid chemical on surfaces and at room temperature to kill disease causing microorganisms.

Less effective than sterilization because it does notkill bacterial endospores


The process intended to kill all microorganisms. It is the highest level of microbial kill that is possible. Sterilizers may be heat, steam, or liquid. The effectiveness of sterilizers are determined by:
1. Mechanical indicators
2. Heat sensitive indicators
3. Biological testing <--- most important

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