| Alphaproteobacteria | |
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| Transmission electron micrograph of Wolbachia within an insect cell. Credit:Public Library of Science / Scott O'Neill |
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| Scientific classification | |
| Domain: | Bacteria |
| Phylum: | Proteobacteria |
| Class: | Alphaproteobacteria |
| Orders | |
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Alphaproteobacteria is a class of Proteobacteria.[1] Like all Proteobacteria, they are Gram-negative.
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The Alphaproteobacteria comprise most phototrophic genera, but also several genera metabolising C1-compounds (e.g., Methylobacterium spp.), symbionts of plants (e.g., Rhizobium spp.) and animals, and a group of pathogens, the Rickettsiaceae. Moreover the precursors of the mitochondria of eukaryotic cells are thought to have originated from Rickettsia spp. in this class (See endosymbiotic theory.). Because of their symbiotic properties, scientists often use Alphaproteobacteria of the genus Agrobacterium to transfer foreign DNA into plant genomes, and they also have many other biotechnological properties.[2]
| Phylogeny of Rickettsiales | |||||||||||||||||||||||||||||||||||||||||||||
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| Robust phylogeny of Rickettsiales from Williams et al. (2007)[3] |
Aerobic anoxygenic phototrophic bacteria are alphaproteobacteria that are a widely distributed marine plankton that may constitute over 10% of the open ocean microbial community.
Families, most of which belonging to the Rhizobiales order, include:
There have been seven orders described.[4]
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