Bacillota is a phylum of bacteria, most of which have gram-positive cell wall structure. 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.
The Clostridia are a highly polyphyletic class of Bacillota, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the class Clostridia are often but not always Gram-positive and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently, most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future.
The Syntrophobacterales are an order of Thermodesulfobacteriota. All genera are strictly anaerobic. Many of the family Syntrophobacteraceae are sulfate-reducing. Some species are motile by using one polar flagellum.
Desulfovibrionaceae is a family of bacteria belonging to the phylum Thermodesulfobacteriota.
Treponema is a genus of spiral-shaped bacteria. The major treponeme species of human pathogens is Treponema pallidum, whose subspecies are responsible for diseases such as syphilis, bejel, and yaws. Treponema carateum is the cause of pinta. Treponema paraluiscuniculi is associated with syphilis in rabbits. Treponema succinifaciens has been found in the gut microbiome of traditional rural human populations.
The Leptospiraceae are a family of spirochete bacteria. It includes the genus Leptospira which contains some pathogenic species.
The Propionibacteriaceae are a family of Gram-positive bacteria found in dairy products or in the intestinal tracts of animals and living in the pores of humans.
Atopobium is a genus of Actinomycetota, in the family Coriobacteriaceae. Atopobium species are anaerobic, Gram-positive rod-shaped or elliptical bacteria found as single elements or in pairs or short chains.
The Erysipelotrichaceae are a family of Gram-positive bacteria.
The Chlamydiaceae are a family of gram-negative bacteria that belongs to the phylum Chlamydiota, order Chlamydiales. Chlamydiaceae species express the family-specific lipopolysaccharide epitope αKdo-(2→8)-αKdo-(2→4)-αKdo. Chlamydiaceae ribosomal RNA genes all have at least 90% DNA sequence identity. Chlamydiaceae species have varying inclusion morphology, varying extrachromosomal plasmid content, and varying sulfadiazine resistance.
The Myxococcota are a phylum of bacteria known as the fruiting gliding bacteria. All species of this group are Gram-negative. They are predominantly aerobic genera that release myxospores in unfavorable environments.
Akkermansia is a genus in the phylum Verrucomicrobiota (Bacteria). The genus was first proposed by Derrien et al. (2004), with the type species Akkermansia muciniphila.
The Selenomonadales are an order of bacteria within the class Negativicutes; unlike most other members of Bacillota, they are Gram-negative. The phylogeny of this order was initially determined by 16S rRNA comparisons. More recently, molecular markers in the form of conserved signature indels (CSIs) have been found specific for all Selenomonadales species. On the basis of these markers, the Selenomonadales are inclusive of two distinct families, and are no longer the sole order within the Negativicutes. Several CSIs have also been found specific for both families, Sporomusaceae and Selenomonadceae. Samples of bacterial strains within this order have been isolated from the root canals of healthy human teeth.
The Nautiliaceae are a family of bacteria placed in an order to itself, Nautiliales, or in the order Campylobacterales. The members of the family are all thermophilic.
The Micrococcales are an order of bacteria in the phylum Actinomycetota.
Euzebya is a genus of Gram-positive bacteria.
The Rhodothermales are an order of bacteria.
Bdellovibrionota is a phylum of bacteria.
The Thermodesulfobacteriaceae are a class of sulfate-reducing bacteria.
Tepidanaerobacteraceae is a family of Gram positive bacteria in the class Clostridia.
