Firmicutes / Bacillota

Most of the microbiota members predominantly belong to just four phyla—the Bacteroidetes, Firmicutes, Actinobacteria, and Proteobacteria
Kim et al. 2017 Immunol Rev. 279(1): 90-105

Firmicutes are obligate anaerobes.
Browne et al. 2017

Most members of the firmicutes are Gram-positive.
Kim et al. 2017 Immunol Rev. 279(1): 90-105

Relative abundance of Firmicutes / Bacillota in the ecosystem

• Soil: 2.9%


• Plant leaf: 7.0%


• Air: 4.8%


• Ocean: 0.0%


• Freshwater: 0.0%


• Human gut: 24.4%

Shin et al. 2015 Trends Biotechnol 33: 496

Firmicutes species from Clostridium cluster XIVa account for almost 60% of the mucin-adhered microbiota
Van den Abbeele et al. 2013 ISME J 7: 949-61

Vancomycin, metronidazole, lacticin 3147 treatments resulted in a decrease in the proportion of sequences assigned to the phyla Firmicutes and Bacteroidetes, with a corresponding increase in those assigned to members of the Proteobacteria
Rea et al. 2011

Bacteroidetes and Firmicutes accounted for 90% of microbial species inhabiting the human gut
Turnbaugh et al. 2007 Nature 449: 804-810
Qin et al. 2010 Nature 464: 59-65
The Human Microbiome Project Consortium 2012 Nature 486(7402): 207-214

After Fecal Microbiota Transplantation (FMT) the recipient microbiota was characterized by increased diversity and increased abundance of Firmicutes
Seekatz et al. 2014 mBio 5(3): e00893-14. doi:10.1128/mBio.00893-14.

Isoflavones and lignans, represent plant-derived chemicals that are metabolized by a diverse array of gut bacteria such as Firmicutes to molecules that bind estrogen receptors and may evoke mammacarcinoma protective effects
Adlercreutz 2007 Critical Reviews in Clinical Laboratory Sciences 44(5–6): 483-525
Lampe 2009
Patisaul & Jefferson 2010

11 known and 11 unknown genera (belonging to Lachnospiraceae and Ruminococcaceae) belong to the core OTUs (>47% of healthy humans) in the healthy human gut
Tap et al. 2009 Environ Microbiol 11: 2574-2584

The 11 known genera are:

• Clostridium


• Eubacterium


• Anaerostipes


• Coprococcus


• Dorea


• Lachnospira


• Roseburia


• Faecalibacterium


• Ruminococcus


• Subdoligranulum


• Coprobacillus

Of the Firmicutes, 95% belong to the Clostridia class, whereas large variations exist in the Bacteroidetes phylotypes among individuals
Finegold et al. 1983 In Human Intestinal Microflora in Health and Disease. Hentges, D.J. (ed.). New York, USA: Academic Press, pp. 3–31
Hayashi et al. 2002 Microbiol Immunol. 46: 535-48
Hold et al. 2002 FEMS Microbiol Ecol. 39: 33-39
Eckburg et al. 2005

Firmicutes include several genera such as Clostridium, Lactobacillus, Ruminococcus, Eubacterium, Fecalibacterium, and Roseburia.
Antonini et al. 2019 Front. Immunol. 10: 1937

Firmicutes mainly comprise gram-positive bacteria with facultative, anaerobic, bacilli, and cocci (14)
Portincasa et al. 2022 Biomedicines 10: 83

Classes