The Bacillota are 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.
Desulfovibrionales are a taxonomic order of bacteria belonging to the phylum Thermodesulfobacteriota, with four families. They are Gram-negative. The majority are sulfate-reducing, with the exception of Lawsonia and Bilophila. All members of this order are obligately anaerobic. Most species are mesophilic, but some are moderate thermophiles.
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 Erysipelotrichaceae are a family of Gram-positive bacteria.
The Halanaerobiales are an order of bacteria placed within the class Clostridia, and encompassing two families, the Halanaerobiaceae and the Halobacteroidaceae. Originally placed within the highly polyphyletic class Clostridia, according to the NCBI and LPSN, it is now thought to lie outside the Bacillota. Halanaerobiales are halophilic obligate anaerobes with a fermentative or homoacetogenic metabolism.
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.
Bacteroidales is an order of bacteria. Notably it includes the genera Prevotella and Bacteroides, which are commonly found in the human gut microbiota.
Caldicellulosiruptor is a genus of thermophilic, anaerobic, Gram-positive, non-spore forming bacteria. Originally placed within the highly polyphyletic class Clostridia, order Thermoanaerobacterales and family Thermoanaerobacterales Family III according to the NCBI and LPSN, it is now thought to lie outside of the Bacillota. Caldicellulosiruptor is known to degrade and ferment complex carbohydrates from plant matter, such as cellulose and hemicellulose, and certain species in the genus have been identified as potential candidates for biofuel production.
Acidaminococcus is a genus in the phylum Bacillota (Bacteria), whose members are anaerobic diplococci that can use amino acids as the sole energy source for growth. Like other members of the class Negativicutes, they are gram-negative, despite being Bacillota, which are normally gram-positive.
Megasphaera is a genus of Bacillota bacteria classified within the class Negativicutes.
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.
Moorella is a genus of bacteria belonging to the phylum Bacillota.
Halanaerobium is a gram-negative, non-endospore-forming, rod-shaped, and strictly anaerobic genus of bacteria from the family Halanaerobiaceae.
The Rhodothermales are an order of bacteria.
Bdellovibrionota is a phylum of bacteria.
Thermosediminibacteraceae is a family of Gram positive bacteria in the class Clostridia.
Tepidanaerobacteraceae is a family of Gram positive bacteria in the class Clostridia.
