halochromatium halochromatium halochromatium is a gram-positive and motile genus of bacteria from the family of chromatiaceae. halochromatium bacteria occur in microbial mats from hypersaline habitates. halochromatium scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: chromatiales family: chromatiaceae genus: halochromatiumimhoff et al. 1998 type species halochromatium salexigens species h. glycolicum h. roseum h. salexigens