azonexus caeni azonexus caeni azonexus caeni is a species of nitrogen-fixing bacteria. it is a root bacteria and together with azonexus fungiphilus and azonexus hydrophilus is one of the three species in the genus. it is gram-negative, motile, non-spore-forming and slightly curved rod-shaped. slu-05t (=dsm 17719t=kctc 12530t=ccbau 10199t) is the type strain. azonexus caeni scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: rhodocyclales family: rhodocyclaceae genus: azonexus species: azonexus caeniquan, im & lee, 2006