Pseudomonadota

American microbiologist Carl Woese established this grouping in 1987, calling it informally the "purple bacteria and their relatives".{{cite journal | vauthors = Woese CR | title = Bacterial evolution | journal = Microbiological Reviews | volume = 51 | issue = 2 | pages = 221–271 | date = June 1987 | pmid = 2439888 | pmc = 373105 | doi = 10.1128/MMBR.51.2.221-271.1987}} The group was later formally named the 'Proteobacteria' after the Greek god Proteus, who was known to assume many forms.{{cite journal | vauthors = Moon CD, Young W, Maclean PH, Cookson AL, Bermingham EN | title = Metagenomic insights into the roles of Proteobacteria in the gastrointestinal microbiomes of healthy dogs and cats | journal = MicrobiologyOpen | volume = 7 | issue = 5 | pages = e00677 | date = October 2018 | pmid = 29911322 | pmc = 6182564 | doi = 10.1002/mbo3.677}} In 2021 the International Committee on Systematics of Prokaryotes designated the synonym Pseudomonadota, and renamed many other prokaryotic phyla as well. This 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.{{cite web | vauthors = Robitzski D | date = 4 January 2022 | work = The Scientist | url=https://www.the-scientist.com/news-opinion/newly-renamed-prokaryote-phyla-cause-uproar-69578 | title=Newly Renamed Prokaryote Phyla Cause Uproar}} The phylum Pseudomonadota encompasses classes Acidithiobacillia, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Hydrogenophilia, and Zetaproteobacteria. The phylum includes a wide variety of pathogenic genera, such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many others.{{cite book | vauthors = Slonczewski JL, Foster JW, Foster E | title = Microbiology: An Evolving Science | edition = 5th | publisher = WW Norton & Company | date = 2020}} Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation.{{Cite journal |last1=Sah |first1=Stuti |last2=Krishnani |first2=Shweena |last3=Singh |first3=Rajni |date=December 2021 |title=Pseudomonas mediated nutritional and growth promotional activities for sustainable food security |journal=Current Research in Microbial Sciences |language=en |volume=2 |pages=100084 |doi=10.1016/j.crmicr.2021.100084 |pmc=8645841 |pmid=34917993}}

Previously, the Pseudomonadota phylum included two additional classes, namely Deltaproteobacteria and Oligoflexia. However, further investigation into the phylogeny of these taxa through genomic marker analysis demonstrated their separation from the Pseudomonadota phylum.{{cite journal | vauthors = Waite DW, Chuvochina M, Pelikan C, Parks DH, Yilmaz P, Wagner M, Loy A, Naganuma T, Nakai R, Whitman WB, Hahn MW, Kuever J, Hugenholtz P | title = Proposal to reclassify the proteobacterial classes Deltaproteobacteria and Oligoflexia, and the phylum Thermodesulfobacteria into four phyla reflecting major functional capabilities | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 70 | issue = 11 | pages = 5972–6016 | date = November 2020 | pmid = 33151140 | doi = 10.1099/ijsem.0.004213 | doi-access = free}} Deltaproteobacteria has been identified as a diverse taxonomic unit, leading to a proposal for its reclassification into distinct phyla: Desulfobacterota (encompassing Thermodesulfobacteria), Myxococcota, and Bdellovibrionota (comprising Oligoflexia).

The class Epsilonproteobacteria was additionally identified within the Pseudomonadota phylum. This class is characterized by its significance as chemolithotrophic primary producers and its metabolic prowess in deep-sea hydrothermal vent ecosystems.{{cite journal | vauthors = Waite DW, Vanwonterghem I, Rinke C, Parks DH, Zhang Y, Takai K, Sievert SM, Simon J, Campbell BJ, Hanson TE, Woyke T, Klotz MG, Hugenholtz P | title = Comparative Genomic Analysis of the Class Epsilonproteobacteria and Proposed Reclassification to Epsilonbacteraeota (phyl. nov.) | journal = Frontiers in Microbiology | volume = 8 | pages = 682 | date = 2017 | pmid = 28484436 | pmc = 5401914 | doi = 10.3389/fmicb.2017.00682 | doi-access = free}} Noteworthy pathogenic genera within this class include Campylobacter, Helicobacter, and Arcobacter. Analysis of phylogenetic tree topology and genetic markers revealed the direct divergence of Epsilonproteobacteria from the Pseudomonadota phylum. Limited outgroup data and low bootstrap values support these discoveries. Despite further investigations, consensus has not been reached regarding the monophyletic nature of Epsilonproteobacteria within Proteobacteria, prompting researchers to propose its taxonomic separation from the phylum. The proposed reclassification of the name Epsilonproteobacteria is Epsilonbacteraeota, later revised to Campylobacterota in 2018.{{cite journal | vauthors = Oren A, Garrity GM | title = Valid publication of the names of forty-two phyla of prokaryotes | journal = Int J Syst Evol Microbiol | year = 2021 | volume = 71 | issue = 10 | pages = 5056 | doi = 10.1099/ijsem.0.005056 | pmid = 34694987 | s2cid = 239887308 | doi-access = free }}

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN){{cite web |author=A.C. Parte |url=https://lpsn.dsmz.de/phylum/pseudomonadota |title=Pseudomonadota |access-date=2025-02-28 |publisher=List of Prokaryotic names with Standing in Nomenclature (LPSN) |display-authors=et al.}} and National Center for Biotechnology Information (NCBI).{{cite web |author=C.L. Schoch |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=1224&lvl=3&lin=f&keep=1&srchmode=1&unlock |title=Pseudomonadota |access-date=2025-02-28 |publisher=National Center for Biotechnology Information (NCBI) taxonomy database |display-authors=et al.}}

The group Pseudomonadota is defined based on ribosomal RNA (rRNA) sequencing, and are divided into several subclasses. These subclasses were regarded as such for many years, but are now treated as various classes of the phylum. These classes are monophyletic.{{cite book | vauthors = Krieg NR, Brenner DJ, Staley JT |title=Bergey's Manual of Systematic Bacteriology |publisher=Springer |year=2005 |isbn=978-0-387-95040-2 |volume= ((2: The Proteobacteria))}}{{cite journal | vauthors = Ciccarelli FD, Doerks T, von Mering C, Creevey CJ, Snel B, Bork P | title = Toward automatic reconstruction of a highly resolved tree of life | journal = Science | volume = 311 | issue = 5765 | pages = 1283–1287 | date = March 2006 | pmid = 16513982 | doi = 10.1126/science.1123061 | bibcode = 2006Sci...311.1283C | s2cid = 1615592 | citeseerx = 10.1.1.381.9514}}{{cite journal | vauthors = Yarza P, Ludwig W, Euzéby J, Amann R, Schleifer KH, Glöckner FO, Rosselló-Móra R | title = Update of the All-Species Living Tree Project based on 16S and 23S rRNA sequence analyses | journal = Systematic and Applied Microbiology | volume = 33 | issue = 6 | pages = 291–299 | date = October 2010 | pmid = 20817437 | doi = 10.1016/j.syapm.2010.08.001| bibcode = 2010SyApM..33..291Y }} The genus Acidithiobacillus, part of the Gammaproteobacteria until it was transferred to class Acidithiobacillia in 2013, was previously regarded as paraphyletic to the Betaproteobacteria according to multigenome alignment studies.{{cite journal | vauthors = Williams KP, Gillespie JJ, Sobral BW, Nordberg EK, Snyder EE, Shallom JM, Dickerman AW | title = Phylogeny of gammaproteobacteria | journal = Journal of Bacteriology | volume = 192 | issue = 9 | pages = 2305–2314 | date = May 2010 | pmid = 20207755 | pmc = 2863478 | doi = 10.1128/JB.01480-09}} In 2017, the Betaproteobacteria was subject to major revisions and the class Hydrogenophilalia was created to contain the order Hydrogenophilales

Pseudomonadota classes with validly published names include some prominent genera:{{cite web |title=Interactive Tree of Life |url=http://itol.embl.de/ |url-status=live |archive-url=https://web.archive.org/web/20220223203638/http://itol.embl.de/ |archive-date=23 February 2022 |access-date=23 February 2022 |publisher=European Molecular Biology Laboratory |place=Heidelberg, DE |language=en}} e.g.:

• Acidithiobacillia: Acidithiobacillus, Thermithiobacillus
• Alphaproteobacteria: Brucella, Rhizobium, Agrobacterium, Caulobacter, Rickettsia, Wolbachia, etc.
• Betaproteobacteria: Bordetella, Ralstonia, Neisseria, Nitrosomonas, etc.
• Gammaproteobacteria: Escherichia, Shigella, Salmonella, Yersinia, Buchnera, Haemophilus, Vibrio, Pseudomonas, Pasteurella, etc.
• Zetaproteobacteria: Mariprofundus

Pseudomonadota are a diverse group. Though some species may stain Gram-positive or Gram-variable in the laboratory, they are nominally Gram-negative. Their unique outer membrane is mainly composed of lipopolysaccharides, which helps differentiate them from the Gram-positive species.{{Cite journal |last1=Silhavy |first1=Thomas J. |last2=Kahne |first2=Daniel |last3=Walker |first3=Suzanne |date=2010-05-01 |title=The Bacterial Cell Envelope |url=http://cshperspectives.cshlp.org/content/2/5/a000414 |journal=Cold Spring Harbor Perspectives in Biology |language=en |volume=2 |issue=5 |pages=a000414 |doi=10.1101/cshperspect.a000414 |issn=1943-0264 |pmc=2857177 |pmid=20452953}} Most Pseudomonadota are motile and move using flagella. Many move about using flagella, but some are nonmotile, or rely on bacterial gliding.{{Cite web |title=Pseudomonadota Garrity et al., 2021 |url=https://www.gbif.org/species/113662549 |access-date=2024-04-18 |website=www.gbif.org |language=en}}

Pseudomonadota have a wide variety of metabolism types. Most are facultative or obligate anaerobes, chemolithoautotrophs, and heterotrophs, though numerous exceptions exist. A variety of distantly related genera within the Pseudomonadota obtain their energy from light through conventional photosynthesis or anoxygenic photosynthesis.

The Acidithiobacillia contain only sulfur, iron, and uranium-oxidizing autotrophs. The type order is the Acidithiobacillaceae, which includes five different Acidithiobacillus species used in the mining industry. In particular, these microbes assist with the process of bioleaching, which involves microbes assisting in metal extraction from mining waste that typically extraction methods cannot remove.{{Citation |last1=Kelly |first1=Donovan P. |title=The Family Acidithiobacillaceae |date=2014 |work=The Prokaryotes: Gammaproteobacteria |pages=15–25 |editor-last=Rosenberg |editor-first=Eugene |url=https://doi.org/10.1007/978-3-642-38922-1_250 |access-date=2024-04-18 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-38922-1_250 |isbn=978-3-642-38922-1 |last2=Wood |first2=Ann P. |editor2-last=DeLong |editor2-first=Edward F. |editor3-last=Lory |editor3-first=Stephen |editor4-last=Stackebrandt |editor4-first=Erko}}

Some Alphaproteobacteria can grow at very low levels of nutrients and have unusual morphology within their life cycles. Some form stalks to help with colonization, and form buds during cell division. Others include agriculturally important bacteria capable of inducing nitrogen fixation in symbiosis with plants. The type order is the Caulobacterales, comprising stalk-forming bacteria such as Caulobacter.{{Citation |last1=Bandopadhyay |first1=Sreejata |title=Soil bacteria and archaea |date=2024 |work=Soil Microbiology, Ecology and Biochemistry |pages=41–74 |url=https://doi.org/10.1016/b978-0-12-822941-5.00003-x |access-date=2024-04-18 |publisher=Elsevier |doi=10.1016/b978-0-12-822941-5.00003-x |isbn=978-0-12-822941-5 |last2=Shade |first2=Ashley}} The mitochondria of eukaryotes are thought to be descendants of an alphaproteobacterium.{{Cite journal |last1=Roger |first1=Andrew J. |last2=Muñoz-Gómez |first2=Sergio A. |last3=Kamikawa |first3=Ryoma |date=November 2017 |title=The Origin and Diversification of Mitochondria |journal=Current Biology |volume=27 |issue=21 |pages=R1177–R1192 |doi=10.1016/j.cub.2017.09.015 |pmid=29112874 |bibcode=2017CBio...27R1177R |issn=0960-9822|doi-access=free}}

The Betaproteobacteria are highly metabolically diverse and contain chemolithoautotrophs, photoautotrophs, and generalist heterotrophs. The type order is the Burkholderiales, comprising an enormous range of metabolic diversity, including opportunistic pathogens. These pathogens are primary for both humans and animals, such as the horse pathogen Burkholderia mallei, and Burkholderia cepacia which causes respiratory tract infections in people with cystic fibrosis.{{Citation |last=Coenye |first=Tom |title=The Family Burkholderiaceae |date=2014 |work=The Prokaryotes: Alphaproteobacteria and Betaproteobacteria |pages=759–776 |editor-last=Rosenberg |editor-first=Eugene |url=https://doi.org/10.1007/978-3-642-30197-1_239 |access-date=2024-04-18 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-30197-1_239 |isbn=978-3-642-30197-1 |editor2-last=DeLong |editor2-first=Edward F. |editor3-last=Lory |editor3-first=Stephen |editor4-last=Stackebrandt |editor4-first=Erko}}

The Gammaproteobacteria are one of the largest classes in terms of genera, containing approximately 250 validly published names. The type order is the Pseudomonadales, which include the genera Pseudomonas and the nitrogen-fixing Azotobacter, along with many others. Besides being a well-known pathogenic genus, Pseudomonas is also capable of biodegradation of certain materials, like cellulose.

The Hydrogenophilalia are thermophilic chemoheterotrophs and autotrophs.{{Cite journal |last1=Wakai |first1=Satoshi |last2=Masanari |first2=Misa |last3=Ikeda |first3=Takumi |last4=Yamaguchi |first4=Naho |last5=Ueshima |first5=Saori |last6=Watanabe |first6=Kaori |last7=Nishihara |first7=Hirofumi |last8=Sambongi |first8=Yoshihiro |date=April 2013 |title=Oxidative phosphorylation in a thermophilic, facultative chemoautotroph, H ydrogenophilus thermoluteolus , living prevalently in geothermal niches |url=https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1758-2229.12005 |journal=Environmental Microbiology Reports |language=en |volume=5 |issue=2 |pages=235–242 |doi=10.1111/1758-2229.12005 |pmid=23584967 |bibcode=2013EnvMR...5..235W |issn=1758-2229}} The bacteria typically use hydrogen gas as an electron donor, but can also use reduced sulfuric compounds. Because of this ability, scientists have begun to use certain species of Hydrogenophilalia to remove sulfides that contaminate industrial wastewater systems. The type order is the Hydrogenophilaceae which contains the genera Thiobacillus, Petrobacter, Sulfuricella, Hydrogenophilus and Tepidiphilus. Currently, no members of this class have been identified as pathogenic.{{Citation |last1=Orlygsson |first1=Johann |title=The Family Hydrogenophilaceae |date=2014 |work=The Prokaryotes: Alphaproteobacteria and Betaproteobacteria |pages=859–868 |editor-last=Rosenberg |editor-first=Eugene |url=https://doi.org/10.1007/978-3-642-30197-1_244 |access-date=2024-04-18 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-30197-1_244 |isbn=978-3-642-30197-1 |last2=Kristjansson |first2=Jakob K. |editor2-last=DeLong |editor2-first=Edward F. |editor3-last=Lory |editor3-first=Stephen |editor4-last=Stackebrandt |editor4-first=Erko}}

The Zetaproteobacteria are the iron-oxidizing neutrophilic chemolithoautotrophs, distributed worldwide in estuaries and marine habitats. This group is so successful in its environment due to their microaerophilic nature. Because they require less oxygen than what is present in the atmosphere, they are able to compete with the abiotic iron(II) oxidation that is already occurring in the environment.{{Cite journal |url=https://academic.oup.com/femsec/article/95/4/fiz015/5304609 |access-date=2024-04-18 |journal=FEMS Microbiology Ecology |doi=10.1093/femsec/fiz015 |pmc=6443915 |pmid=30715272 |title=The Fe(II)-oxidizing Zetaproteobacteria: Historical, ecological and genomic perspectives |date=2019 |volume=95 |issue=4 | vauthors = McAllister SM, Moore RM, Gartman A, Luther GW, Emerson D, Chan CS}} The only confirmed type order for this class is the Mariprofundaceae, which does not contain any known pathogenic species.{{Citation |last1=Moreira |first1=Ana Paula B. |title=The Family Mariprofundaceae |date=2014 |work=The Prokaryotes: Deltaproteobacteria and Epsilonproteobacteria |pages=403–413 |editor-last=Rosenberg |editor-first=Eugene |url=https://doi.org/10.1007/978-3-642-39044-9_378 |access-date=2024-04-18 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-642-39044-9_378 |isbn=978-3-642-39044-9 |last2=Meirelles |first2=Pedro M. |last3=Thompson |first3=Fabiano |editor2-last=DeLong |editor2-first=Edward F. |editor3-last=Lory |editor3-first=Stephen |editor4-last=Stackebrandt |editor4-first=Erko}}

Transformation, a process in which genetic material passes from one bacterium to another,{{cite journal | vauthors = Johnston C, Martin B, Fichant G, Polard P, Claverys JP | title = Bacterial transformation: distribution, shared mechanisms and divergent control | journal = Nature Reviews. Microbiology | volume = 12 | issue = 3 | pages = 181–196 | date = March 2014 | pmid = 24509783 | doi = 10.1038/nrmicro3199 | s2cid = 23559881}} has been reported in at least 30 species of Pseudomonadota distributed in the classes alpha, beta, and gamma.{{cite journal | vauthors = Johnsborg O, Eldholm V, Håvarstein LS | title = Natural genetic transformation: prevalence, mechanisms and function | journal = Research in Microbiology | volume = 158 | issue = 10 | pages = 767–778 | date = December 2007 | pmid = 17997281 | doi = 10.1016/j.resmic.2007.09.004 | doi-access = free}} The best-studied Pseudomonadota with respect to natural genetic transformation are the medically important human pathogens Neisseria gonorrhoeae (class beta), and Haemophilus influenzae (class gamma).{{cite journal | vauthors = Michod RE, Bernstein H, Nedelcu AM | title = Adaptive value of sex in microbial pathogens | journal = Infection, Genetics and Evolution | volume = 8 | issue = 3 | pages = 267–285 | date = May 2008 | pmid = 18295550 | doi = 10.1016/j.meegid.2008.01.002| bibcode = 2008InfGE...8..267M }} Natural genetic transformation is a sexual process involving DNA transfer from one bacterial cell to another through the intervening medium and the integration of the donor sequence into the recipient genome. In pathogenic Pseudomonadota, transformation appears to serve as a DNA repair process that protects the pathogen's DNA from attack by their host's phagocytic defenses that employ oxidative free radicals.

Due to the distinctive nature of each of the six classes of Pseudomonadota, this phylum occupies a multitude of habitats. These include:

• Human oral cavity{{cite journal | vauthors = Leão I, de Carvalho TB, Henriques V, Ferreira C, Sampaio-Maia B, Manaia CM | title = Pseudomonadota in the oral cavity: a glimpse into the environment-human nexus | journal = Applied Microbiology and Biotechnology | volume = 107 | issue = 2–3 | pages = 517–534 | date = February 2023 | pmid = 36567346 | pmc = 9842593 | doi = 10.1007/s00253-022-12333-y}}
• Microbial mats in the deep sea{{cite journal | vauthors = Williams KP, Kelly DP | title = Proposal for a new class within the phylum Proteobacteria, Acidithiobacillia classis nov., with the type order Acidithiobacillales, and emended description of the class Gammaproteobacteria | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 63 | issue = Pt 8 | pages = 2901–2906 | date = August 2013 | pmid = 23334881 | doi = 10.1099/ijs.0.049270-0}}
• Marine sediments
• Thermal sulfur springs{{cite journal | vauthors = Boden R, Hutt LP, Rae AW | title = Reclassification of Thiobacillus aquaesulis (Wood & Kelly, 1995) as Annwoodia aquaesulis gen. nov., comb. nov., transfer of Thiobacillus (Beijerinck, 1904) from the Hydrogenophilales to the Nitrosomonadales, proposal of Hydrogenophilalia class. nov. within the 'Proteobacteria', and four new families within the orders Nitrosomonadales and Rhodocyclales | journal = International Journal of Systematic and Evolutionary Microbiology | volume = 67 | issue = 5 | pages = 1191–1205 | date = May 2017 | pmid = 28581923 | doi = 10.1099/ijsem.0.001927 | hdl-access = free | hdl = 10026.1/8740}}
• Agricultural soil
• Hydrothermal vents{{cite journal | vauthors = Emerson D, Rentz JA, Lilburn TG, Davis RE, Aldrich H, Chan C, Moyer CL | title = A novel lineage of proteobacteria involved in formation of marine Fe-oxidizing microbial mat communities | journal = PLOS ONE | volume = 2 | issue = 7 | pages = e667 | date = August 2007 | pmid = 17668050 | pmc = 1930151 | doi = 10.1371/journal.pone.0000667 | doi-access = free | bibcode = 2007PLoSO...2..667E}}
• Stem nodules of legumes
• Within aphids as endosymbionts
• Gastrointestinal tract of warm-blooded species
• Brackish, estuary waters
• Microbiomes of shrimp and mollusks
• Human vaginal tract
• Potato rhizosphere microbiome

Studies have suggested Pseudomonadota as a relevant signature of disease in the human gastrointestinal (GI) tract, by operating as a marker for microbiota instability. The human gut microbiome consists mainly of four phyla: Firmicutes, Bacteroidetes, Actinobacteria, and Pseudomonadota. Microorganism gut colonization is dynamic from birth to death, with stabilization at the first few years of life, to higher diversity in adults, to reduced diversity in the elderly. The gut microbiome conducts processes like nutrient synthesis, chemical metabolism, and the formation of the gut barrier. Additionally, the gut microbiome facilitates host interactions with its surrounding environment through regulation of nutrient absorption and bacterial intake. In 16s rRNA and metagenome sequencing studies, Proteobacteria have been identified as bacteria that prompts endotoxemia (an inflammatory gut response) and metabolic disorders in human GI tracts. Another study by Michail et al. showed a correlation of microbial composition in children with and without nonalcoholic fatty liver disease (NAFLD), wherein patients with NAFLD have a higher abundance of Gammaproteobacteria than patients without the disease.{{cite journal | vauthors = Michail S, Lin M, Frey MR, Fanter R, Paliy O, Hilbush B, Reo NV | title = Altered gut microbial energy and metabolism in children with non-alcoholic fatty liver disease | journal = FEMS Microbiology Ecology | volume = 91 | issue = 2 | pages = 1–9 | date = February 2015 | pmid = 25764541 | pmc = 4358749 | doi = 10.1093/femsec/fiu002 | doi-access = free}}

Classes Betaproteobacteria and Gammaproteobacteria are prevalent within the human oral cavity, and are markers for good oral health. The oral microbiome consists of 11 habitats, including the tongue dorsum, hard palate, tonsils, throat, saliva, and more.{{cite journal | vauthors = Jia G, Zhi A, Lai PF, Wang G, Xia Y, Xiong Z, Zhang H, Che N, Ai L | title = The oral microbiota - a mechanistic role for systemic diseases | journal = British Dental Journal | volume = 224 | issue = 6 | pages = 447–455 | date = March 2018 | pmid = 29569607 | doi = 10.1038/sj.bdj.2018.217 | doi-access = free}} Changes in the oral microbiome are due to endogenous and exogenous factors like host lifestyle, genotype, environment, immune system, and socioeconomic status. Considering diet as a factor, high saturated fatty acid (SAF) content, achieved through poor diet, has been correlated to increased abundance of Betaproteobacteria in the oral cavity.

Pseudomonadota bacteria have a symbiotic or mutualistic association with plant roots, an example being in the rhizomes of potato plants.{{Cite journal |last1=García-Serquén |first1=Aura L. |last2=Chumbe-Nolasco |first2=Lenin D. |last3=Navarrete |first3=Acacio Aparecido |last4=Girón-Aguilar |first4=R. Carolina |last5=Gutiérrez-Reynoso |first5=Dina L. |date=2024-02-17 |title=Traditional potato tillage systems in the Peruvian Andes impact bacterial diversity, evenness, community composition, and functions in soil microbiomes |journal=Scientific Reports |language=en |volume=14 |issue=1 |page=3963 |doi=10.1038/s41598-024-54652-2 |issn=2045-2322 |pmc=10874408 |pmid=38368478|bibcode=2024NatSR..14.3963G}} Because of this symbiotic relationship, farmers have the ability to increase their crop yields. Healthier root systems can lead to better nutrient uptake, improved water retention, increased resistance to diseases and pests, and ultimately higher crop yields per acre.{{Cite journal |last1=Hartman |first1=Kyle |last2=Schmid |first2=Marc W. |last3=Bodenhausen |first3=Natacha |last4=Bender |first4=S. Franz |last5=Valzano-Held |first5=Alain Y. |last6=Schlaeppi |first6=Klaus |last7=van der Heijden |first7=Marcel G.A. |date=2023-07-31 |title=A symbiotic footprint in the plant root microbiome |journal=Environmental Microbiome |language=en |volume=18 |issue=1 |page=65 |doi=10.1186/s40793-023-00521-w |doi-access=free |issn=2524-6372 |pmc=10391997 |pmid=37525294|bibcode=2023EMicb..18...65H}} Increased agricultural output can spark economic growth, contribute to food security, and lead to job creation in rural areas.{{Cite journal |last1=Mozumdar |first1=Lavlu |date=2012 |title=Agricultural productivity and food security in the developing world |url=https://ageconsearch.umn.edu/record/196764 |journal=Bangladesh Journal of Agricultural Economics |language=en |volume=35 |doi=10.22004/AG.ECON.196764}}

As briefly mentioned in previous sections, members of Pseudomonadota have vast metabolic abilities that allow them to utilize and produce a variety of compounds. Bioleaching, done by various Thiobacillus species, are a primary example of this.{{cite journal |last1=Bosecker |first1=Klaus |title=Bioleaching: metal solubilization by microorganisms |journal=FEMS Microbiology Reviews |date=July 1997 |volume=20 |issue=3–4 |pages=591–604 |doi=10.1111/j.1574-6976.1997.tb00340.x}} Any iron and sulfur oxidizing species has the potential to uncover metals and low-grade ores that conventional mining techniques were unable to extract. At present, they are most often used for recovering copper and uranium, but researchers are looking to expand this field in the future. The downside of this method is that the bacteria produce acidic byproducts that end up in acid mine drainage. Bioleaching has significant economic promise if it can be controlled and not cause any further harm to the environment.

Pseudomonadota are microbes commonly found within soil systems. Microbes play a crucial role in the surrounding ecosystem by performing functions such as nutrient cycling, carbon dioxide fixation, decomposition, and nitrogen fixation.{{Citation |last1=Gupta |first1=Ankit |title=Microbes and Environment |date=2017 |journal=Principles and Applications of Environmental Biotechnology for a Sustainable Future |pages=43–84 |editor-last=Singh |editor-first=Ram Lakhan |place=Singapore |publisher=Springer Singapore |language=en |doi=10.1007/978-981-10-1866-4_3 |isbn=978-981-10-1865-7 |pmc=7189961 |last2=Gupta |first2=Rasna |last3=Singh |first3=Ram Lakhan}} Pseudomonadota can be described as phototrophs, heterotrophs, and lithotrophs. As heterotrophs (examples Pseudomonas and Xanthomonas) these bacteria are effective in breaking down organic matter, contributing to nutrient cycling. Additionally, photolithotrophs within the phylum are able to perform photosynthesis using sulfide or elemental sulfur as electron donors, which enables them to participate in carbon fixation and oxygen production even in anaerobic conditions. These Pseudomonadota bacteria are also considered copiotrophic organisms, meaning they can be found in environments with high nutrient availability. These environments have ample sources of carbon and other nutrients, environments like fertile soils, compost, and sewage. These copiotrophic bacteria are able to enhance soil health by performing nutrient cycling and waste decomposition.

Because this phylum are able to form a symbiotic relationship with plant roots, incorporating Pseudomonadota into agricultural practices aligns with principles of sustainable farming.{{Cite journal |last1=Mapelli |first1=Francesca |last2=Mengoni |first2=Alessio |last3=Riva |first3=Valentina |last4=Borin |first4=Sara |date=January 2023 |title=Bacterial culturing is crucial to boost sustainable agriculture |url=https://linkinghub.elsevier.com/retrieve/pii/S0966842X22002888 |journal=Trends in Microbiology |language=en |volume=31 |issue=1 |pages=1–4 |doi=10.1016/j.tim.2022.10.005|hdl=2434/945499 |hdl-access=free}} These bacteria contribute to soil health and fertility, promote natural pest management, and enhance the resilience of crops to environmental stressors.

• List of bacteria genera
• List of bacterial orders

{{reflist|30em}}

{{Wikispecies}}

• [http://www.palaeos.org/Proteobacteria Pseudomonadota information] from Palaeos. {{Webarchive|url=https://web.archive.org/web/20100523075109/http://www.palaeos.org/Proteobacteria |date=2010-05-23}}

{{Portal bar|Biology}}

{{Life on Earth}}

{{Bacteria classification}}

{{Bacterial cutaneous infections}}

{{Gram-negative bacterial diseases}}

{{Taxonbar|from1=Q12962137|from2=Q130999}}

Category:Gram-negative bacteria

Category:Bacteria phyla