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Proteobacteria is a major
phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a q ...
of
Gram-negative bacteria Gram-negative bacteria are bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few microm ...
. They include a wide variety of
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory ...
ic genera, such as ''
Escherichia ''Escherichia'' is a genus of Gram-negative, non-Endospore, spore-forming, Facultative anaerobic organism, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointest ...
'', ''
Salmonella ''Salmonella'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruse ...
'', ''
Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne illness, foodborne infection, usually associated with eating undercooked seafood. Typically found in Seawater, s ...
'', ''
Helicobacter ''Helicobacter'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
'', ''
Yersinia ''Yersinia'' is a genus of bacteria in the family Yersiniaceae. ''Yersinia'' species are Gram-negative, coccobacilli bacteria, a few micrometers long and fractions of a micrometer in diameter, and are facultative anaerobes. Some members of ''Yers ...

Yersinia
'', ''
Legionellales The Legionellales are an order of Proteobacteria. Like all Proteobacteria, they are Gram-negative.George M. Garrity: ''Bergey's Manual of Systematic Bacteriology''. 2. Auflage. Springer, New York, 2005, Volume 2: ''The Proteobacteria, Part B: The ...
'', and many others. Others are free-living (non
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
) and include many of the
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
responsible for
nitrogen fixation Nitrogen fixation is a chemical process by which molecular (), with a strong triple , in the is converted into () or related nitrogenous compounds, typically in soil or aquatic systems but also . Atmospheric nitrogen is molecular , a relativel ...
.
Carl Woese Carl Richard Woese (; July 15, 1928 – December 30, 2012) was an American microbiologist A microbiologist (from Greek ) is a scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an B ...

Carl Woese
established this grouping in 1987, calling it informally the "purple bacteria and their relatives". Because of the great diversity of forms found in this group, it was named after
Proteus Image:Proteus-Alciato.gif, Illustration of Proteus by Andrea Alciato from ''The Book of Emblems'' (1531) In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bod ...

Proteus
, a Greek god of the sea capable of assuming many different shapes and is not named after the Proteobacteria genus ''
Proteus Image:Proteus-Alciato.gif, Illustration of Proteus by Andrea Alciato from ''The Book of Emblems'' (1531) In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bod ...
''.


Characteristics

All "Proteobacteria" are Gram-negative (though some may stain Gram-positive or Gram-variable in practice), with an outer membrane mainly composed of
lipopolysaccharide Lipopolysaccharides (LPS), also known as endotoxins, are large molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an e ...

lipopolysaccharide
s. Many move about using
flagella A flagellum (; ) is a hairlike appendage that protrudes from a wide range of microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an organism () is any organic, life, living system that fu ...
, but some are nonmotile or rely on
bacterial gliding Gliding motility is a type of translocation used by microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an organism () is any organic, life, living system that functions as an individual ent ...

bacterial gliding
. The latter include the
myxobacteria The myxobacteria ("slime bacteria") are a group of bacteria that predominantly live in the soil and feed on insoluble organic substances. The myxobacteria have very large genomes relative to other bacteria, e.g. 9–10 million nucleotides except ...
, an order of bacteria that can aggregate to form multicellular fruiting bodies. Also, a wide variety in the types of
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such as Cell signaling, signaling and self-sustaining ...

metabolism
exists. Most members are facultatively or obligately
anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Anaerobic adhesive, a bonding ag ...
,
chemolithoautotrophicA lithoautotroph or chemolithoautotroph is a microbe which derives energy from reduced compounds of mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Ea ...
, and
heterotrophic A heterotroph (; from Ancient Greek "other" and "nutrition") is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are prim ...
, but numerous exceptions occur. A variety of genera, which are not closely related to each other, convert energy from light through
photosynthesis Photosynthesis is a process used by plants and other organisms to into that, through , can later be released to fuel the organism's activities. Some of this chemical energy is stored in molecules, such as s and es, which are synthesized fro ...

photosynthesis
and
anoxygenic photosynthesis Bacterial anoxygenic photosynthesis is differentiated from the more renowned terrestrial plant oxygenic photosynthesis by method of a terminal reductant that is (e.g. hydrogen sulfide Hydrogen sulfide is the chemical compound with the chemical f ...
. "Proteobacteria" are associated with the imbalance of
microbiota Microbiota are "ecological communities of commensal, symbiotic and pathogenic microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usu ...
of the lower reproductive tract of women. These species are associated with inflammation. Some
Alphaproteobacteria Alphaproteobacteria is a Class (biology), class of bacteria in the phylum Proteobacteria (See also bacterial taxonomy). Its members are highly diverse and possess few commonalities, but nevertheless share a common ancestor. Like all ''Proteobacter ...
can grow at very low levels of nutrients and have unusual morphology such as stalks and buds. Others include agriculturally important bacteria capable of inducing nitrogen fixation in symbiosis with plants. The type order is the
Caulobacterales Caulobacteraceae is a family of proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia'', '' ...
, comprising stalk-forming bacteria such as ''
Caulobacter
Caulobacter
''. The
mitochondria A mitochondrion (; ) is a double-membrane Image:Schematic size.jpg, up150px, Schematic of size-based membrane exclusion A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, i ...

mitochondria
of eukaryotes are thought to be descendants of an alphaproteobacterium. The
Betaproteobacteria Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Proteobacteria. The ''Betaproteobacteria'' are a class comprising over 75 genus, genera and 400 species of bacteria. Together, the ''Betaproteoba ...
are highly metabolically diverse and contain chemolithoautotrophs,
photoautotrophPhotoautotrophs are organisms that use light energy and inorganic carbon to produce organic materials. Eukaryotic photoautotrophs utilize absorb energy through the chlorophyll molecules in their chloroplasts while prokaryotic photoautotrophs use chlo ...
s, and generalist
heterotroph A heterotroph (; from Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek ...
s. The type order is the
Burkholderiales The Burkholderiales are an order of Proteobacteria.George M. Garrity: ''Bergey's Manual of Systematic Bacteriology''. 2. Auflage. Springer, New York, 2005, Vol. 2: ''The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria'' ...
, comprising an enormous range of metabolic diversity, including
opportunistic pathogen An opportunistic infection is an infection An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multiplication, and the reaction of host (biology), host tissues to the infectiou ...
s. The
Gammaproteobacteria The class Gammaproteobacteria belongs to the Proteobacteria phylum and contains about 250 genera, which makes it the most genera-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically important groups of bacteria belon ...
are the largest class in terms of species with validly published names. The type order is the
Pseudomonadales The Pseudomonadales are an order of Proteobacteria. A few members are opportunistic pathogens, such as species of ''Pseudomonas'', ''Moraxella'', and ''Acinetobacter'', which may cause pneumonia. ''Pseudomonas'' The bacterial genus ''Pseudomonas ...
, which include the genera ''
Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 validly described species. The members of the genus demonstrate a great deal of Metabolism, metabolic diversity and conse ...

Pseudomonas
'' and the nitrogen-fixing ''
Azotobacter ''Azotobacter'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
''. The
Deltaproteobacteria The Deltaproteobacteria are a class of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia ...
include bacteria that are predators on other bacteria and are important contributors to the anaerobic side of the sulfur cycle. The type order is the
Myxococcales The myxobacteria ("slime bacteria") are a group of bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganism ...
, which includes organisms with self-organising abilities such as '' Myxococcus'' spp. The
Epsilonproteobacteria Epsilonproteobacteria are a class of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia' ...
are often slender, Gram-negative rods that are helical or curved. The type order is the
Campylobacterales The Campylobacterales are an order of Proteobacteria which make up the epsilon subdivision, together with the small family Nautiliaceae. Like all Proteobacteria, they are Gram-negative. Most of the species are microaerophilic.Garrity, George M.; B ...
, which includes important food pathogens such as ''
Campylobacter ''Campylobacter'' (meaning "curved bacteria") is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classificat ...

Campylobacter
'' spp. The
Zetaproteobacteria The class Zetaproteobacteria is the sixth and most recently described class of the Proteobacteria. Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria were originally represented by a single de ...
are iron-oxidizing
neutrophilic Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocyte Granulocytes are a category of white blood cells in the innate immune system characterized by the presence of specific granules in their cytoplas ...
chemolithoautotrophs, distributed worldwide in estuaries and marine habitats. The type order is the Mariprofundales. The
Hydrogenophilalia The class Hydrogenophilalia in the ''Bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a f ...
are obligate thermophiles and include heterotrophs and autotrophs. The type order is the Hydrogenophilales. The
Acidithiobacillia ''Acidithiobacillia'' is a class of the "''Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Ye ...
contain only sulfur, iron, and uranium-oxidising
autotroph An autotroph or primary producer is an organism that produces complex organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bo ...
s. The type order is the
Acidithiobacillales The Acidithiobacillales are an order of bacteria within the class ''Acidithiobacillia'' and comprises the genera ''Acidithiobacillus'' and ''Thermithiobacillus''. Originally, both were included in the genus ''Thiobacillus'', but they are not relat ...
, which includes economically important organisms used in the mining industry such as ''
Acidithiobacillus ''Acidithiobacillus'' is a genus of the ''Acidithiobacillia'' in the ''"Proteobacteria"''. The genus includes acidophilic organisms capable of iron and/or sulfur oxidation. Like all ''"Proteobacteria"'', ''Acidithiobacillus'' spp. are Gram-negati ...
'' spp. The
Oligoflexia The Oligoflexia are a class of the phylum ''Proteobacteria''. All species of this group are all Proteobacteria, Gram-negative. It has been proposed that the ''Oligoflexia'' be split into four new phyla: ''Desulfobacterota'', ''Myxococcota'', ''Bd ...
are filamentous aerobes. The type order is the Oligoflexales, which contains the genus '' Oligoflexus''.


Taxonomy

The group is defined primarily in terms of
ribosomal RNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA A non-coding RNA (ncRNA) is an RNA Ribonucleic acid (RNA) is a polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consis ...
(rRNA) sequences. The "Proteobacteria" are divided into nine classes with validly published names, referred to by the
Greek letters#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
alpha through zeta, the Acidithiobacillia, Hydrogenophilalia, and Oligoflexia. These were previously regarded as subclasses of the phylum, but they are now treated as
classes Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently f ...
. These classes are
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...
. The genus ''
Acidithiobacillus ''Acidithiobacillus'' is a genus of the ''Acidithiobacillia'' in the ''"Proteobacteria"''. The genus includes acidophilic organisms capable of iron and/or sulfur oxidation. Like all ''"Proteobacteria"'', ''Acidithiobacillus'' spp. are Gram-negati ...
'', part of the Gammaproteobacteria until it was transferred to class Acidithiobacillia in 2013, was previously regarded as
paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—Monophyly, monophyletic subgroups. The group is said to be paraphyleti ...
to the ''Betaproteobacteria'' according to multigenome alignment studies. In 2017, the
Betaproteobacteria Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Proteobacteria. The ''Betaproteobacteria'' are a class comprising over 75 genus, genera and 400 species of bacteria. Together, the ''Betaproteoba ...
was subject to major revisions and the class
Hydrogenophilalia The class Hydrogenophilalia in the ''Bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a f ...
was created to contain the order Hydrogenophilales Proteobacterial classes with validly published names include some prominent genera:Interactive Tree of Life
/ref> e.g.: *
Alphaproteobacteria Alphaproteobacteria is a Class (biology), class of bacteria in the phylum Proteobacteria (See also bacterial taxonomy). Its members are highly diverse and possess few commonalities, but nevertheless share a common ancestor. Like all ''Proteobacter ...
: ''
Brucella ''Brucella'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their ...

Brucella
,
Rhizobium ''Rhizobium'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses ...
,
Agrobacterium ''Agrobacterium'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
, ,
Rickettsia ''Rickettsia'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circ ...
,
Wolbachia ''Wolbachia'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their ...

Wolbachia
'', etc. *
Betaproteobacteria Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Proteobacteria. The ''Betaproteobacteria'' are a class comprising over 75 genus, genera and 400 species of bacteria. Together, the ''Betaproteoba ...
: ''
Bordetella ''Bordetella'' () is a genus of small (0.2 – 0.7 µm), gram-negative coccobacilli of the phylum Proteobacteria. ''Bordetella'' species, with the exception of ''Bordetella petrii, B. petrii'', are obligate aerobes, as well as highly fastidio ...
, Ralstonia,
Neisseria ''Neisseria'' is a large genus of bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a fe ...
,
Nitrosomonas ''Nitrosomonas'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
'', etc. *
Gammaproteobacteria The class Gammaproteobacteria belongs to the Proteobacteria phylum and contains about 250 genera, which makes it the most genera-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically important groups of bacteria belon ...
: ''
Escherichia ''Escherichia'' is a genus of Gram-negative, non-Endospore, spore-forming, Facultative anaerobic organism, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointest ...
,
Shigella ''Shigella'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to ...
,
Salmonella ''Salmonella'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruse ...
,
Yersinia ''Yersinia'' is a genus of bacteria in the family Yersiniaceae. ''Yersinia'' species are Gram-negative, coccobacilli bacteria, a few micrometers long and fractions of a micrometer in diameter, and are facultative anaerobes. Some members of ''Yers ...

Yersinia
, Buchnera,
Haemophilus ''Haemophilus'' is a genus of Gram-negative, pleomorphism (microbiology), pleomorphic, coccobacillus, coccobacilli bacteria belonging to the family Pasteurellaceae. While ''Haemophilus'' bacteria are typically small coccobacilli, they are catego ...

Haemophilus
,
Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne illness, foodborne infection, usually associated with eating undercooked seafood. Typically found in Seawater, s ...
,
Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 validly described species. The members of the genus demonstrate a great deal of Metabolism, metabolic diversity and conse ...

Pseudomonas
'', etc. *
Deltaproteobacteria The Deltaproteobacteria are a class of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia ...
: ''
Desulfovibrio ''Desulfovibrio'' is a genus of Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized by their cell envelo ...
,
Geobacter ''Geobacter'' is a genus of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia'', ''Leg ...
,
Bdellovibrio ''Bdellovibrio'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
'', etc. *
Epsilonproteobacteria Epsilonproteobacteria are a class of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Yersinia' ...
: ''
Helicobacter ''Helicobacter'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
,
Campylobacter ''Campylobacter'' (meaning "curved bacteria") is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classificat ...

Campylobacter
,
Wolinella The genus ''Wolinella'' is a member of the Campylobacterales order of Bacteria. The order Campylobacterales includes human pathogens such as ''Helicobacter pylori'' and ''Campylobacter jejuni''. Strains The only publicly available strain of ''Wol ...
'', etc. *
Zetaproteobacteria The class Zetaproteobacteria is the sixth and most recently described class of the Proteobacteria. Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria were originally represented by a single de ...
: '' Mariprofundus, Ghiorsea'' *
Oligoflexia The Oligoflexia are a class of the phylum ''Proteobacteria''. All species of this group are all Proteobacteria, Gram-negative. It has been proposed that the ''Oligoflexia'' be split into four new phyla: ''Desulfobacterota'', ''Myxococcota'', ''Bd ...
: '' Oligoflexus''. *
Acidithiobacillia ''Acidithiobacillia'' is a class of the "''Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicobacter'', ''Ye ...
: ''
Acidithiobacillus thiooxidans ''Acidithiobacillus thiooxidans'', formerly known as ''Thiobacillus thiooxidans'' until its reclassification into the newly designated genus ''Acidithiobacillus'' of the Acidithiobacillia subclass of Proteobacteria, is a Gram-negative, rod-shaped ...
'', '' Thermithiobacillus tepidarius'' *
Hydrogenophilalia The class Hydrogenophilalia in the ''Bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a f ...
: '' Hydrogenophilus thermoluteolus'', '' Tepidiphilus margaritifer''


Transformation

Transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Transf ...
, a process in which genetic material passes from one bacterium to another, has been reported in at least 30 species of "Proteobacteria" distributed in the classes alpha, beta, gamma and epsilon. The best-studied "Proteobacteria" with respect to natural genetic transformation are the medically important human pathogens ''
Neisseria gonorrhoeae ''Neisseria gonorrhoeae'', also known as ''gonococcus'' (singular), or ''gonococci'' (plural), is a species of Gram-negative diplococci bacteria isolated by Albert Ludwig Sigesmund Neisser, Albert Neisser in 1879. It causes the sexually transmit ...

Neisseria gonorrhoeae
'' (class beta), ''
Haemophilus influenzae ''Haemophilus influenzae'' (formerly called Pfeiffer's bacillus or ''Bacillus influenzae'') is a Gram-negative, Coccobacillus, coccobacillary, facultative anaerobic organism, facultatively anaerobic Capnophile, capnophilic pathogenic bacteriu ...

Haemophilus influenzae
'' (class gamma) and ''
Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophile, microaerophilic, spiral bacteria, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, ...

Helicobacter pylori
'' (class epsilon). 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 "Proteobacteria", transformation appears to serve as a
DNA repair DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene mol ...

DNA repair
process that protects the pathogen's DNA from attack by their host's phagocytic defenses that employ oxidative free radicals.


References


External links


Proteobacteria information
from
Palaeos Palaeos.com is a web site on biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, ...
.
Proteobacteria.
– J. P. Euzéby: List of Prokaryotic names with Standing in Nomenclature. {{Taxonbar, from=Q130999 Gram-negative bacteria Bacteria phyla