Alphaproteobacteria (Α-proteobacteria)

Alphaproteobacteria is a 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 Proteobacteria, its members are Gram-negative and some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable.

— Wikipedia