49-471: Gammaproteobacteria is a class of bacteria in the phylum Pseudomonadota (synonym Proteobacteria ). It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes . Several medically, ecologically, and scientifically important groups of bacteria belong to this class. All members of this class are Gram-negative . It is the most phylogenetically and physiologically diverse class of
98-415: 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. 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
147-496: 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. Most Pseudomonadota are motile and move using flagella. Many move about using flagella , but some are nonmotile, or rely on bacterial gliding . Pseudomonadota have
196-683: 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. Noteworthy pathogenic genera within this class include Campylobacter , Helicobacter , and Arcobacter . Analysis of phylogenetic tree topology and genetic markers revealed
245-426: 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
294-411: A symbiotic relationship with plant roots, incorporating Pseudomonadota into agricultural practices aligns with principles of sustainable farming . These bacteria contribute to soil health and fertility, promote natural pest management, and enhance the resilience of crops to environmental stressors. Wohlfahrtiimonas W. chitiniclastica W. larvae W. populi Wohlfahrtiimonas
343-427: A variety of compounds. Bioleaching , done by various Thiobacillus species, are a primary example of this. 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
392-475: A well-known pathogenic genus, Pseudomonas is also capable of biodegradation of certain materials, like cellulose. The Hydrogenophilalia are thermophilic chemoheterotrophs and autotrophs. 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
441-431: 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
490-733: A wide variety of ecological niches: on the ground, within plants, or deep on the ocean floor. On the land, it has been reported that Gammaproteobacteria species have been isolated from Robinia pseudoacacia and other plants, while in the deep sea a sulfur-oxidizing gammaproteobacteria was found in a hydrothermal vent chimney; by entering into symbiotic relationships in deep sea areas, sulfur-oxidizing chemolithotrophic microbes receive additional organic hydrocarbons in hydrothermal ecosystems. Some Gammaproteobacteria are symbiotic with geothermic ocean vent-downwelling animals, and in addition, Gammaproteobacteria can have complex relationships with other species that live around thermal springs, for example, with
539-632: A widespread and essential community in the oceans. Methanotrophs , such as the order Methylococcales , metabolize methane as sole energy source and are very important in the global carbon cycle . They are found in any site with methane sources, like gas reserves , soils, and wastewater . Purple sulfur bacteria are anoxygenic phototrophs that oxidize sulfur, but potentially also other substrates like iron. They are represented by members of two families, Chromatiaceae (e.g. Allochromatium , Chromatium , Thiodicyton ) and Ectothiorhodospiraceae (e.g. Ectothiorhodospira ). A few species within
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#1732851288286588-1173: Is (as of 2010) still very difficult to resolve the phylogeny of this bacterial class. The following molecular phylogeny of Gammaproteobacteria is based on a set of 356 protein families. Betaproteobacteria Xanthomonadales Chromatiales Methylococcus Beggiatoa Legionellales Ruthia , Vesicomyosocius , Thiomicrospira , Dichelobacter , Francisella Moraxellaceae , Alcanivorax Saccharophagus Oceanospirillaceae Marinobacter Pseudomonadaceae Pseudoalteromonadaceae , Alteromonas , Idiomarinaceae Shewanellaceae Psychromonadaceae Aeromonadales Vibrionales Pasteurellales Enterobacterales A number of genera in Gammaproteobacteria have not yet been assigned to an order or family. These include Alkalimonas , Gallaecimonas , Ignatzschineria , Litorivivens , Marinicella , Plasticicumulans , Pseudohongiella , Sedimenticola , Thiohalobacter , Thiohalorhabdus , Thiolapillus , and Wohlfahrtiimonas . Gammaproteobacteria , especially
637-472: Is a genus of bacteria from the class Gammaproteobacteria . It was first described by Tóth et al. in 2008, and is named after its first described vector: the larvae of Wohlfahrtia magnifica , a species of parasitic fly. Other species of flies, such as Lucilia sericata , Chrysomya megacephala and Musca domestica have also been linked closely to the spread of Wohlfahrtiimonas, as human wounds that have been infected with fly larvae are breeding grounds for
686-406: Is correlated with higher relative abundance of Alphaproteobacteria , Betaproteobacteria and Gammaproteobacteria . The relative abundance of Betaproteobacteria and Gammaproteobacteria is also positively correlated to the dissolved organic carbon (DOC) concentration, which is a key environmental parameter shaping bacterial community composition. Gammaproteobacteria are also key players in
735-490: Is present in the atmosphere, they are able to compete with the abiotic iron(II) oxidation that is already occurring in the environment. The only confirmed type order for this class is the Mariprofundaceae , which does not contain any known pathogenic species. Transformation , a process in which genetic material passes from one bacterium to another, has been reported in at least 30 species of Pseudomonadota distributed in
784-730: 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. 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
833-705: 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. 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
882-633: Is the Caulobacterales , comprising stalk-forming bacteria such as Caulobacter . The mitochondria of eukaryotes are thought to be descendants of an alphaproteobacterium. 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
931-542: Is the Hydrogenophilaceae which contains the genera Thiobacillus, Petrobacter, Sulfuricella, Hydrogenophilus and Tepidiphilus . Currently, no members of this class have been identified as pathogenic. 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
980-508: The Gammaporteobacteria class have been detected, and the most important among them are Beggiatoa , Thioploca and Thiomargarita ; besides, large amounts of hydrogen sulfide are produced by sulfate-reducing bacteria in organic-rich coastal sediments. Marine Gammaproteobacteria include aerobic anoxygenic phototrophic bacteria (AAP) that use bacteriochlorophyll to support the electron transport chain . They are believed to be
1029-753: The Pseudomonadota . Members of Gammaproteobacteria live in several terrestrial and marine environments, in which they play various important roles, including in extreme environments such as hydrothermal vents . They can have different shapes, rods, curved rods, cocci, spirilla, and filaments, and include free living bacteria, biofilm formers, commensals and symbionts; some also have the distinctive trait of being bioluminescent. Diverse metabolisms are found in Gammaproteobacteria ; there are both aerobic and anaerobic (obligate or facultative) species, chemolithoautotrophics , chemoorganotrophics , photoautotrophs and heterotrophs . The element " gamma " (third letter of
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#17328512882861078-420: The bacteria responsible for nitrogen fixation . 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. Deltaproteobacteria has been identified as a diverse taxonomic unit, leading to
1127-589: The "purple bacteria and their relatives". The group was later formally named the 'Proteobacteria' after the Greek god Proteus, who was known to assume many forms. 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
1176-586: The Greek alphabet) indicates that this is Class III in Bergey's Manual of Systematic Bacteriology (Vol. II, page 1). Proteus refers to the Greek sea god who could change his shape. Bacteria (Greek βακτήριον; "rod" "little stick"), in terms of etymological history, refers to Bacillus (rod-shaped bacteria), but in this case is "useful in the interim while the phylogenetic data are being integrated into formal bacterial taxonomy." Currently, many different classifications are based on different approaches, such as It
1225-410: The classes alpha, beta, and gamma. 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). Natural genetic transformation is a sexual process involving DNA transfer from one bacterial cell to another through the intervening medium and the integration of
1274-409: The dark carbon fixation in coastal sediments, which are the largest carbon sink on Earth, and the majority of these bacteria have not been cultured yet. The deep-sea hydrothermal system is one of the most extreme environments on Earth. Almost all vent-endemic animals are strongly associated with the primary production of the endo- and/or episymbiotic chemoautotrophic microorganisms. Analyses of both
1323-471: 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
1372-436: 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: Studies have suggested Pseudomonadota as
1421-463: The earlier name Proteobacteria, of long standing in the literature. 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. Others are free-living (non- parasitic ) and include many of
1470-535: 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
1519-578: The genera Acinetobacter , Colwellia , Glaciecola , Halomonas , Marinobacter , Marinomonas , Methylomonas , Pseudoalteromonas , Pseudomonas , Rhodanobacter , Shewanella , Stenotrophomonas , and Vibrio . The most widespread pathway for carbon fixation among Gammaproteobacteria is the Calvin–Benson–Bassham (CBB) cycle , although a minority may use the rTCA cycle. Thioflavicoccus mobilis (a free living species) and " Candidatus Endoriftia persephone" (symbiont of
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1568-796: The genus Thermomonas (order Lysobacter ) carry out the same metabolism. Numerous genera are obligate or generalist hydrocarbonclasts . The obligate hydrocarbonoclastic bacteria (OHCB) use hydrocarbons almost exclusively as a carbon source; until now they have been found only in the marine environment. Examples include Alcanivorax , Oleiphilus , Oleispira , Thalassolitus , Cycloclasticus and Neptunomonas , and some species of Polycyclovorans , Algiphilus (order Xanthomonadales ), and Porticoccus hydrocarbonoclasticus (order Cellvibrionales ) that were isolated from phytoplankton. In contrast, aerobic “generalist” hydrocarbon degraders can use either hydrocarbons or nonhydrocarbon substrates as sources of carbon and energy; examples are found in
1617-450: The giant tubeworm Riftia pachyptila ) may use the rTCA cycle in addition to the CBB cycle, and may express these two different pathways simultaneously. Symbiosis is a close and a long-term biological interaction between two different biological organisms. A large number of Gammaproteobacteria are able to join in a close endosymbiosis with various species. Evidence for this can be found in
1666-495: The horse pathogen Burkholderia mallei , and Burkholderia cepacia which causes respiratory tract infections in people with cystic fibrosis. 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
1715-406: The marine environment, several species from this class can infect different marine organisms, such as species in the genus Vibrio which affect fish, shrimp, corals or oysters, and species of Salmonella which affect grey seals ( Halichoerus grypus ). Pseudomonadota Pseudomonadota (synonym Proteobacteria ) is a major phylum of Gram-negative bacteria . Currently, they are considered
1764-524: The members of Nitrosococcus (with the exception of Nitrosococcus mobilis ) and they are also obligate halophilic bacteria . Others are chemoautotrophic sulfur-oxidizers, like Thiotrichales , which are found in communities such as filamentous microbial biofilms in the Tor Caldara shallow-water gas vent in the Tyrrhenian Sea . Moreover, thanks to 16S rRNA gene analysis, different sulfide oxidizers in
1813-468: The most environmentally friendly and sustainable energy production systems. They are also used as biological methane filters. Phototrophic purple sulfur bacteria are used in wastewater treatment processes. The ability of some Gammaproteobacteria (e.g. the genus Alcanivorax ) to bioremediate oil is increasingly important for degrading crude oil after oil spills. Some species from the family Chromatiaceae are notable because they may be involved in
1862-665: The name Epsilonproteobacteria is Epsilonbacteraeota , later revised to Campylobacterota in 2018. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LSPN) and the National Center for Biotechnology Information (NCBI). 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
1911-704: The oral cavity. Pseudomonadota bacteria have a symbiotic or mutualistic association with plant roots, an example being in the rhizomes of potato plants. 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. Increased agricultural output can spark economic growth, contribute to food security, and lead to job creation in rural areas. As briefly mentioned in previous sections, members of Pseudomonadota have vast metabolic abilities that allow them to utilize and produce
1960-857: The order Hydrogenophilales Pseudomonadota classes with validly published names include some prominent genera: e.g.: Alphaproteobacteria Zetaproteobacteria Gammaproteobacteria Betaproteobacteria Hydrogenophilalia Alphaproteobacteria " Mariprofundia " ( Zetaproteobacteria ) " Thiohalorhabdales " Methylothermaceae 2 Algiphilaceae Methylothermaceae Acidithiobacillia Gammaproteobacteria (nested Betaproteobacteria & Hydrogenophilalia ) " Caulobacteria " ( Alphaproteobacteria ) " Mariprofundia " ( Zetaproteobacteria ) " Magnetococcia " clade 1 "Foliamicales" clade 3 Immundisolibacterales clade 5 "Acidithiobacillidae" ( Acidithiobacillia ) "Neisseriidae" ( Betaproteobacteria & nested Hydrogenophilalia ) "Pseudomonadidae" ( Gammaproteobacteria ) Pseudomonadota are
2009-470: The orders Alteromonadales and Vibrionales , are fundamental in marine and coastal ecosystems because they are the major groups involved in nutrient cycling. Despite their fame as pathogens, they find application in a huge number of fields, such as bioremediation and biosynthesis. Gammaproteobacteria can be used as a microbial fuel cell (MFC) element that applies their ability to dissimilate various metals. The produced energy could be collected as one of
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2058-640: 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
2107-536: The phylum. These classes are monophyletic . 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 . In 2017, the Betaproteobacteria was subject to major revisions and the class Hydrogenophilalia was created to contain
2156-551: The predominant phylum within the realm of bacteria. They are naturally found as pathogenic and free-living (non- parasitic ) genera. The phylum comprises six classes Acidithiobacillia , Alphaproteobacteria , Betaproteobacteria , Gammaproteobacteria , Hydrogenophilia , and Zetaproteobacteria . The Pseudomonadota are widely diverse, with differences in morphology , metabolic processes, relevance to humans, and ecological influence. American microbiologist Carl Woese established this grouping in 1987, calling it informally
2205-477: The primary production in these unique ecosystems. In the last decades, it has been found that orders belonging to Gammaproteobacteria , like Pseudomonas , Moraxella , are able to degrade different types of plastics and these microbes might have a key role in plastic biodegradation. Gammaproteobacteria are metabolically diverse, employing a variety of electron donors for respiration and biosynthesis. Some groups are nitrite-oxidizers and ammonia oxidizers like
2254-857: The production of vitamin B12 . Some Gammaproteobacteria are used to synthesize poly-b-hydroxyalkanoate (PHA), which is a polymer that is used in the production of biodegradable plastics . Many Gammaproteobacteria species are able to generate secondary metabolites with antibacterial properties. Gammaproteobacteria are widely distributed and abundant in various ecosystems such as soil, freshwater lakes and rivers, oceans and salt lakes. For example, they constitute about 6–20% (average of 14%) of bacterioplankton in different oceans, and they are distributed world-wide in both deep-sea and coastal sediments. In seawater, bacterial community composition could be shaped by environmental parameters such as phosphorus availability, total organic carbon, salinity, and pH. In soil, higher pH
2303-860: The shrimp Rimicaris exoculata living from hydrothermal vents on the Mid-Atlantic Ridge . Regarding the endosymbionts, most of them lack many of their family characteristics due to significant genome reduction. Gammaproteobacteria include several medically and scientifically important groups of bacteria, such as the families Enterobacteriaceae , Vibrionaceae , and Pseudomonadaceae . A number of human pathogens belong to this class, including Yersinia pestis , Vibrio cholerae , Pseudomonas aeruginosa , Escherichia coli , and some species of Salmonella . The class also contains plant pathogens such as Xanthomonas axonopodis pv. citri ( citrus canker ), Pseudomonas syringae pv. actinidiae ( kiwifruit Psa outbreak), and Xylella fastidiosa . In
2352-636: The symbiotic and free-living microbial communities in the various deep-sea hydrothermal environments have revealed a predominance in biomass of members of the Gammaproteobacteria . Gammaproteobacteria have a wide diversity, metabolic versatility, and functional redundancy in the hydrothermal sediments, and they are responsible for the important organic carbon turnover and nitrogen and sulfur cycling processes. Anoxic hydrothermal fluids contain several reduced compounds such as H 2 , CH 4 , and reduced metal ions in addition to H 2 S. Chemoautotrophs that oxidize hydrogen sulfide and reduce oxygen potentially sustain
2401-407: The tongue dorsum, hard palate , tonsils, throat, saliva, and more. 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
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