isochromatium isochromatium isochromatium is a gram-negative, obligately phototrophic and strictly anaerobic genus of bacteria from the family of chromatiaceae with one known species (isochromatium buderi). isochromatium scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: chromatiales family: chromatiaceae genus: isochromatiumimhoff et al. 1998 type species isochromatium buderi species i. buderi