| Bacillota | |
|---|---|
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| Bacillus subtilis,Gram-stained | |
Scientific classification | |
| Domain: | Bacteria |
| Kingdom: | Bacillati |
| Phylum: | Bacillota Gibbons and Murray 2021[1] |
| Classes | |
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| Synonyms | |
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Bacillota (synonymFirmicutes) is aphylum ofbacteria, most of which havegram-positivecell wall structure.[2] The renaming of phyla such as Firmicutes in 2021 remains controversial among microbiologists, many of whom continue to use the earlier names of long standing in the literature.[3]
The name "Firmicutes" was derived from the Latin words for "tough skin," referring to the thick cell wall typical of bacteria in this phylum. Scientists once classified the Firmicutes to include all gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low-G+C group, in contrast to theActinomycetota. They have round cells, called cocci (singular coccus), or rod-like forms (bacillus). A few Firmicutes, such asMegasphaera,Pectinatus,Selenomonas andZymophilus, have a porous pseudo-outer membrane that causes them to staingram-negative.
Many Bacillota (Firmicutes) produceendospores, which are resistant todesiccation and can survive extreme conditions. They are found in various environments, and the group includes some notable pathogens. Those in one family, theheliobacteria, produce energy throughanoxygenic photosynthesis. Bacillota play an important role in beer, wine, and cider spoilage.
The group is typically divided into theClostridia, which areanaerobic, and theBacilli, which are obligate or optionalaerobes.[citation needed]
Onphylogenetic trees, the first two groups show up asparaphyletic orpolyphyletic, as do their main genera,Clostridium andBacillus.[4] However, Bacillota as a whole is generally believed to be monophyletic, or paraphyletic with the exclusion ofMollicutes.[5]
The currently accepted taxonomy based on theList of Prokaryotic names with Standing in Nomenclature (LPSN)[6] and theNational Center for Biotechnology Information (NCBI).[7]
The Firmicutes are thought by some[8] to be the source of thearchaea, by models there the archaea branched relatively late from bacteria, rather than forming an independently originating early lineage (domain of life) from the last universal common ancestor of cellular life (LUCA).[citation needed]
| 16S rRNA basedLTP_01_2022[9][10][11] | GTDB 08-RS214 byGenome Taxonomy Database[12][13][14] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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♦ Paraphyletic Firmicutes |
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More than 274 genera were considered as of 2016[update] to be within the Bacillota phylum,[citation needed] notable genera of Bacillota include:
Bacilli, orderBacillales
Bacilli, orderLactobacillales
 | This sectionmay presentfringe theories, without givingappropriate weight to the mainstream view and explaining the responses to the fringe theories. Pleasehelp improve it or discuss the issue on thetalk page.(March 2021) (Learn how and when to remove this message) |
Bacillota make up ~30% of the mouse andhuman gut microbiome.[15][failed verification] The phylum Bacillota as part of thegut microbiota has been shown to be involved in energy resorption, and potentially related to the development ofdiabetes andobesity.[16][17][18][19] Within the gut of healthy human adults, the most abundant bacterium:Faecalibacterium prausnitzii (F. prausnitzii), which makes up 5% of the total gut microbiome, is a member of the Bacillota phylum. This species is directly associated with reduced low-grade inflammation in obesity.[20]F. prausnitzii has been found in higher levels within the guts of obese children than in non-obese children.
In multiple studies a higher abundance of Bacillota has been found in obese individuals than in lean controls. A higher level ofLactobacillus (of the Bacillota phylum) has been found in obese patients and in one study, obese patients put on weight loss diets showed a reduced amount of Bacillota within their guts.[21]
Diet changes in mice have also been shown to promote changes in Bacillota abundance. A higher relative abundance of Bacillota was seen in mice fed a western diet (high fat/high sugar) than in mice fed a standard low fat/ high polysaccharide diet. The higher amount of Bacillota was also linked to more adiposity and body weight within mice.[22] Specifically, within obese mice, the classMollicutes (within the Bacillota phylum) was the most common. When the microbiota of obese mice with this higher Bacillota abundance was transplanted into the guts of germ-free mice, the germ-free mice gained a significant amount of fat as compared to those transplanted with the microbiota of lean mice with lower Bacillota abundance.[23]
The presence ofChristensenella (Bacillota, in class Clostridia), isolated from humanfaeces, has been found to correlate with lowerbody mass index.[24]
