Proteobacteria

Based on rRNA sequences, the phylum Proteobacteria is divided into 5 sections – α, β, γ, δ, ε. These are often treated as classes and contain numerous orders, each of which may include families. The Gamma (γ)Proteobacteria are paraphyletic to the Beta (β) Proteobacteria.

Division >>> Alphaproteobacteria (α)
The Alphaproteobacteria comprise phototrophic genera, several genera metabolizing C1-compounds, symbionts, and the pathogenic Rickettsiaceae (Rocky Mountain Spotted Fever, etc.) It is thought that the precursors of eukaryotic mitochondria originated from endosymbioisis of Rickettsiales.
>> Order Caulobacterales > Genus Caulobacter
>> Order Rhizobiales > Genus Agrobacterium, Bradyrhizobium, Brucella, Methylobacterium, Prosthecomicrobium, Rhizobium, Rhodopseudomonas, Sinorhizobium
>> Order Rhodobacterales > Genus Rhodobacter, Roseobacter
>> Order Rhodospirales > Genus Acetobacter, Rhodospirillum
>> Order Rickettsiales > Genus Rickettsia (Mitochondria), Wolbachia
>> Order Sphingomonadales > Genus Erythrobacter, Erythromicrobium, Sphingomonas

Division >>> Betaproteobacteria (β)
The Betaproteobacteria comprise several groups of aerobic of facultative bacteria, chemolithotrophic genera (Nitrosomonas), and some phototrophs (genera Rhodocyclus and Rubrivivax). Many of them are found in environmental samples, such as waste water or soil. Pathogenic species within this class include the Neisseriaceae (causing gonorrhoe and meningoencephalitis) and species of the genus Burkholderia.
>> Order Burkholderiales > Genus Alcaligenes, Burkholderia, Leptothrix, Sphaerotilus
>> Order Hydrogenophilales > Genus Thiobacillus
>> Order Neisseriales > Genus Neisseria
>> Order Nitrosomonadales > Genus Nitrosomonas, Gallionella, Spirillum
>> Order Rhodocyclales > Genus Azoarcus

Division >>> Gammaproteobacteria (γ)
The order Chromatiales (photosynthetic purple sulfur bacteria) belong to this class, and include families Chromatiaceae and Ectothiorhodospiraceae, which produce internal and external sulfur granules respectively, and which exhibit differences in the structure of their internal membranes. The non-photosynthetic family-genus Halothiobacillus is also included in order Chromatiales The Gammaproteobacteria comprise several medically and scientifically important groups of bacteria, such as the Enterobacteriaceae, Vibrionaceae and Pseudomonadaceae. An exceeding number of important pathogens belongs to this class, e.g. Salmonella (causing enteritis and typhoid fever), Yersinia (plague), Vibrio (cholera), Pseudomonas aeruginosa (pulmonary infections in hospitalised or cystic fibrosis patients).
>> Order Aeromonadales > Genus Aeromonas, Succinomonas, Succinivibrio, Ruminobacter
>> Order Chromatiales (purple sulfur) > Genus Nitrosococcus, Thiocapsa
>> Order Enterobacteriales > Genus Enterobacter, Escherichia, Klebsiella, Salmonella, Wigglesworthia, Yersinia
>> Order Legionellales > Genus Coxiella, Legionella
>> Order Oceanospirales > Genus Halomonas
>> Order Pasteurellales > Genus Pasteurella>> Order Pseudomonadales > Genus Acinetobacter, Azotobacter, Pseudomonas, Psychrobacter
>> Order Thiotrichales > Genus Beggiatoa, Thiomargarita
>> Order Vibrionales > Genus Vibrio
>> Order Xanthomonadales > Genus Xanthomonas

Deltaproteobacteria (δ)
The Deltaproteobacteria comprise a predominantly aerobic genera, fruiting-body-forming myxobacteria, and strictly anaerobic genera, which includess most of the known sulfate- (Desulfovibrio, Desulfobacter, Desulfococcus, Desulfonema, etc.) and sulfur-reducing bacteria (e.g. Desulfuromonas) in addition to several other anaerobic bacteria with different physiology (e.g. ferric iron-reducing Geobacter and syntrophic (growing together) Pelobacter and Syntrophus species).

Division >>> Proteobacteria (Delta/Epsilon)
>> Order Campylobacterales > Genus Campylobacter, Helicobacter
>> Order Myxococcales > Genus Myxococcus
>> Order Desulfobacterales > Genus Desulfosarcina
>> Order Desulfuromonadales > Genus Geobacter Desulfuromonas

Epsilonproteobacteria (ε)
The Epsilonproteobacteria comprise only a few genera, mainly the curved to spirilloid Wolinella, Helicobacter, and Campylobacter. This class of Proteobacteria inhabit the digestive tract of animals and humans, serving as symbionts (Wolinella in cows) or as pathogens (Helicobacter in the stomach, Campylobacter in the duodenum).

Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.