Cultural and Biochemical Characteristics of the Genus Chromobacterium

Abstract

Summary: The cultural and biochemical characteristics of 38 strains of Chromobacterium are described. They are non-sporing aerobic Gram-negative rods which produce a violet pigment and possess both polar monotrichous and peritrichous flagella. They produce little acidity from carbohydrates and utilize citrate. Two main groups of strains were distinguishable, a mesophilic and a psychrophilic group. The former usually ferment glucose anaerobically, are markedly proteolytic, facultatively anaerobic, and give a positive egg-yolk reaction, but do not hydrolyse aesculin. The psychrophilic organisms produce acid from glucose but only aerobically, are poorly proteolytic, strictly aerobic, and hydrolyse aesculin but do not produce an egg-yolk reaction. Chromobacterium viscosum Grimes, C. iodinum Davis and C. ianthinum Gilman have been re-examined; they should be excluded from the genus. The nomenclature of the genus is confused. Proposals have therefore been made to the International Committee on Bacteriological Nomenclature that the mesophilic species should be called Chromobacterium violaceum and the psychrophilic species C. lividum, and neotype strains have been suggested.