Alphaproteobacteria
Agrobacterium tumefaciens ( Rhizobiales ) to a carrot cell (secondary electron micrograph )
Alphaproteobacteria (also α - Proteobacteria ) refers to a class in the phylogenetic system of the bacteria, which have been prepared on the basis of the base sequence of the 16S ribosomal ribonucleic acid ( 16S rRNA). The phylum (the tribe ) Proteobacteria is divided into 5 classes Alphaproteobacteria to Epsilonproteobacteria. The Alphaproteobacteria, like all classes of the tribe, gram negative.
Among the Alphaproteobacteria are the orders
- Caulobacterales Henrici & Johnson 1935
- Kiloniellales Wiese et al. 2009
- Kordiimonadales Kwon et al. 2005
- " Parvularculales "
- Rhizobiales Kuykendall 2006
- Rhodobacterales Garrity et al. 2006
- Rhodospirillales Pfennig & Trüper 1971
- Rickettsiales Gieszczykiewicz 1939
- Sneathiellales Kurahashi et al. 2008
- Sphingomonadales Yabuuchi & Kosako 2006
And numerous, yet not sure unclassified isolates.
Important examples are to be found among others in the genera Rhodospirillum, Acetobacter, Rickettsia, Paracoccus, Zymomonas, Rhizobium, Bartonella, Brucella and Nitrobacter. Among the Alphaproteobacteria numerous aquatic living species occur. High levels of these bacteria in water samples often indicate oligotrophic conditions.