Chromatium

Gram-negative, ovoid to rod-shaped bacteria, phototrophic, use ammonia as a nitrogen source. Some are found only in sulfide-containing freshwater habitats exposed to light while others may occur in marine, estuarine, and freshwater environments. Motile by means of polar flagella. Described by PERTY, 1852. Zur Kenntnis kleinster Lebensformen. Jent and Reinert, Bern I-VIII, 1-228.

Chromatium is a genus of photoautotrophic Gram-negative bacteria which are found in water. The cells are straight rod-shaped or slightly curved. They belong to the purple sulfur bacteria and oxidize sulfide to produce sulfur which is deposited in intracellular granules of the cytoplasm.