Pseudomonadota is a major phylum of Gram-negative bacteria. The renaming of several prokaryote phyla in 2021, including Pseudomonadota, remains controversial among microbiologists, many of whom continue to use the earlier name Proteobacteria, of long standing in the literature. The phylum Proteobacteria includes a wide variety of pathogenic genera, such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many others. Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation.
The Burkholderiales are an order of Pseudomonadota. Like all Pseudomonadota, they are Gram-negative. They include several pathogenic bacteria, including species of Burkholderia, Bordetella, and Ralstonia. They also include Oxalobacter and related genera, which are unusual in using oxalic acid as their source of carbon. Other well-studied genera include Alcaligenes, Cupriavidus, Achromobacter, Comamonas, Delftia, Massilia, Duganella, Janthinobacterium, Polynucleobacter, non-pathogenic Paraburkholderia, Caballeronia, Polaromonas, Thiomonas, Collimonas, Hydrogenophaga, Sphaerotilus, Variovorax, Acidovorax, Rubrivivax and Rhodoferax, and Herbaspirillum.
In taxonomy, the Halobacteriaceae are a family of the Halobacteriales in the domain Archaea. Halobacteriaceae represent a large part of halophilic Archaea, along with members in two other methanogenic families, Methanosarcinaceae and Methanocalculaceae. The family consists of many diverse genera that can survive extreme environmental niches. Most commonly, Halobacteriaceae are found in hypersaline lakes and can even tolerate sites polluted by heavy metals. They include neutrophiles, acidophiles, alkaliphiles, and there have even been psychrotolerant species discovered. Some members have been known to live aerobically, as well as anaerobically, and they come in many different morphologies. These diverse morphologies include rods in genus Halobacterium, cocci in Halococcus, flattened discs or cups in Haloferax, and other shapes ranging from flattened triangles in Haloarcula to squares in Haloquadratum, and Natronorubrum. Most species of Halobacteriaceae are best known for their high salt tolerance and red-pink pigmented members, but there are also non-pigmented species and those that require moderate salt conditions. Some species of Halobacteriaceae have been shown to exhibit phosphorus solubilizing activities that contribute to phosphorus cycling in hypersaline environments. Techniques such as 16S rRNA analysis and DNA-DNA hybridization have been major contributors to taxonomic classification in Halobacteriaceae, partly due to the difficulty in culturing halophilic Archaea.
Alcaligenes is a genus of Gram-negative, aerobic, rod-shaped bacteria in the order of Burkholderiales.
The Desulfurococcales are an order of the Thermoprotei, part of the kingdom Archaea. The order encompasses some genera which are all thermophilic, autotrophs which utilise chemical energy, typically by reducing sulfur compounds using hydrogen.
Methanobacterium is a genus of the Methanobacteriaceae family of Archaea. Despite the name, this genus belongs not to the bacterial domain but the archaeal domain. Methanobacterium are nonmotile and live without oxygen. Some members of this genus can use formate to reduce methane; others live exclusively through the reduction of carbon dioxide with hydrogen. They are ubiquitous in some hot, low-oxygen environments, such as anaerobic digestors, their wastewater, and hot springs.
In taxonomy, Methanospirillum is a genus of microbes within the family Methanospirillaceae. All its species are methanogenic archaea. The cells are bar-shaped and form filaments. Most produce energy via the reduction of carbon dioxide with hydrogen, but some species can also use formate as a substrate. They are Gram-negative and move using archaella on the sides of the cells. They are strictly anaerobic, and they are found in wetland soil and anaerobic water treatment systems.
Nisaea is a genus in the phylum Pseudomonadota (Bacteria), which contains two species, namely N. denitrificans and N. nitritireducens, which were described in 2008.
Cupriavidus gilardii is a Gram-negative, aerobic, motile, oxidase-positive bacterium from the genus Cupriavidus and the family Burkholderiaceae. It is motil by a single polar flagellum. It is named after G. L. Gilardi, an American microbiologist. The organism was initially identified as Ralstonia gilardii in 1999, renamed Wautersiella gilardii, and most recently moved into the genus Cupriavidus after 16S rRNA gene sequencing revealed it to be most closely related to Cupriavidus necator. Notably, species of this genus are not inhibited by copper due to the production of chelation factors, and may actually be stimulated by the presence of copper.
Halomonas pacifica is a bacterium of the genus Halomonas.
Kerstersia gyiorum is a Gram-negative, catalase-positive, oxidase-negative, bacterium of the genus Kerstersia, isolated from various human clinical samples.
Arthrobacter monumenti is a bacterium species from the genus Arthrobacter which has been isolated from biofilms covering a Servilia tomb in Carmona, Spain.
Pelotomaculum is a Gram-positive strictly anaerobic, mesophilic, thermophilic and non-motile bacterial genus from the family of Peptococcaceae.
Carboxydocella is a Gram-positive and obligate anaerobe bacterial genus from the family of Syntrophomonadaceae.
Bulleidia is a Gram-positive, non-spore-forming, anaerobic and non-motile genus from the family of Erysipelotrichidae, with one known species.
Haloferacaceae is a family of halophilic, chemoorganotrophic or heterotrophic archaea within the order Haloferacales. The type genus of this family is Haloferax. Its biochemical characteristics are the same as the order Haloferacales.
Heliorestis is an alkaliphilic genus of bacteria from the family of Heliobacteriaceae.
The Eggerthellaceae are a family of Gram-positive, rod- or coccus-shaped Actinomycetota. It is the sole family within the order Eggerthellales.
Natrialbales is an order of halophilic, chemoorganotrophic archaea within the class Haloarchaea. The type genus of this order is Natrialba.
Haloferacales is an order of halophilic, chemoorganotrophic or heterotrophic archaea within the class Haloarchaea. The type genus of this order is Haloferax.
