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Bacillus subtilis, Gram stained
Scientific classification


The Firmicutes are a phylum of bacteria, most of which have the Gram-positive type of cell walls.

Classes[change | change source]

The group is typically divided into the Clostridia, which are anaerobic, the Bacilli, which are aerobic, and the Mollicutes, a class of bacteria which do not have cell walls.

On phylogenetic trees, the first two groups show up as paraphyletic or polyphyletic, as do their main genera, Clostridium and Bacillus.[1]

Health[change | change source]

Firmicutes make up the largest portion of the mouse and human gut microbiome.[2] The division Firmicutes as part of the gut flora has been shown to be involved in energy resorption and obesity.[3][4][5]

References[change | change source]

  1. Wolf M.; et al. (2004). "Phylogeny of Firmicutes with special reference to Mycoplasma (Mollicutes) as inferred from phosphoglycerate kinase amino acid sequence data". Int. J. Syst. Evol. Microbiol. 54 (Pt 3): 871–5. doi:10.1099/ijs.0.02868-0. PMID 15143038. Archived from the original on 2012-12-09. Retrieved 2014-03-28.
  2. "Ecological and evolutionary forces shaping microbial diversity in the human intestine". Cell (Review). 124 (4): 837–48. 2006. doi:10.1016/j.cell.2006.02.017. PMID 16497592. S2CID 17203181. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
  3. "Microbial ecology: human gut microbes associated with obesity". Nature (Clinical Trial). 444 (7122): 1022–3. 2006. doi:10.1038/4441022a. PMID 17183309. S2CID 205034045. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
  4. Henig, Robin Marantz (2006-08-13). "Fat Factors". New York Times Magazine. Retrieved 2008-09-28.
  5. Ley R.E.; et al. (2005). "Obesity alters gut microbial ecology". Proc. Natl. Acad. Sci. U.S.A. (Research Support). 102 (31): 11070–5. doi:10.1073/pnas.0504978102. PMC 1176910. PMID 16033867.