kidzsearch.com > wiki   Explore:web images videos games  

Gut flora

KidzSearch Safe Wikipedia for Kids.
Jump to: navigation, search



Bacteria make up most of the flora in the colon[7] and up to 60% of the dry mass of faeces.[2] Somewhere between 300[2] and 1000 different species live in the gut,[3] with most estimates at about 500.[4][5][8] However, it is probable that 99% of the bacteria come from about 30 or 40 species.[9] Fungi and protozoa also make up a part of the gut flora, but little is known about their activities.


Over 99% of the bacteria in the gut are anaerobic,[2][3][7][9][10] but in the cecum, aerobic bacteria reach high densities.[2]

The traditional view is that no metazoan phylum can break down cellulose by producing the enzyme cellulase. Instead, herbivores contain, in their gut, microorganisms which produce cellulase.[11][12] This is important because cellulose is the most common organic compound on Earth. About 33% of all plant matter is cellulose (the cellulose content of cotton is 90% and that of wood is 40–50%).[13] Recently, evidence has emerged that some animals do produce their own cellulase.[14] The question is not yet quite settled.[15]

Related pages


  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Guarner F, Malagelada JR (February 2003). "Gut flora in health and disease". Lancet 361 (9356): 512–9. doi:10.1016/S0140-6736(03)12489-0 . PMID 12583961 . 
  4. 4.0 4.1 4.2 Steinhoff U (June 2005). "Who controls the crowd? New findings and old questions about the intestinal microflora". Immunol. Lett. 99 (1): 12–6. doi:10.1016/j.imlet.2004.12.013 . PMID 15894105 . 
  5. 5.0 5.1 O'Hara A.M. & Shanahan F. 2006. The gut flora as a forgotten organ. EMBO Report 7: 688–93. PMID 16819463.
  6. Junjie Qin; et al. (2009). "A human gut microbial gene catalogue established by metagenomic sequencing". Nature 464 (7285): 59–65. doi:10.1038/nature08821 . PMID 20203603 . http://www.nature.com/nature/journal/v464/n7285/full/nature08821.html. Retrieved 2010-03-06 
  7. 7.0 7.1 7.2 University of Glasgow. 2005. The normal gut flora. Available through web archive. Accessed May 22, 2008
  9. 9.0 9.1 Beaugerie L, Petit JC (April 2004). "Microbial-gut interactions in health and disease. Antibiotic-associated diarrhoea". Best Pract Res Clin Gastroenterol 18 (2): 337–52. doi:10.1016/j.bpg.2003.10.002 . PMID 15123074 . http://linkinghub.elsevier.com/retrieve/pii/S1521691803001276. 
  10. Vedantam G, Hecht DW (October 2003). "Antibiotics and anaerobes of gut origin". Curr. Opin. Microbiol. 6 (5): 457–61. doi:10.1016/j.mib.2003.09.006 . PMID 14572537 . http://linkinghub.elsevier.com/retrieve/pii/S1369527403001176. 
  11. Cleveland L.R. 1923. Symbiosis between termites and their intestinal protozoa. Proc Natl Acad Sci U S A 9(12): 424–428.
  12. Hobson P.N; & Stewart C.S. 1997. The rumen microbial ecosystem. 2nd ed, Springer, New York. ISBN 0-7514-0366-0.
  13. Chemical Composition of Wood
  14. Watanabe H, Tokuda G (2001). "Animal cellulases". Cell. Mol. Life Sci 58: 1167–1178. doi:10.1007/PL00000931 . 
  15. Tokuda, G; Watanabe, H (2007). "Hidden cellulases in termites: revision of an old hypothesis". Biology Letters 3 (3): 336–339. doi:10.1098/rsbl.2007.0073 . PMC 2464699 . PMID 17374589 . http://rsbl.royalsocietypublishing.org/content/3/3/336.long