acidovorax caeni acidovorax caeni acidovorax caeni is a gram-negative, catalase- and oxidase-positive, rod-shaped bacterium from the comamonadaceae family that was isolated from the activated sludge of a wastewater treatment plant in belgium. colonies are yellow–brown. acidovorax caeni scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: burkholderiales family: comamonadaceae genus: acidovorax species: a. caeni binomial name acidovorax caeniheylen et al. 2008, sp. nov. type strain dsm 19327, heylen r-24608, lmg 24103, r-24608