Chromatium

**Definition:** A genus of gram-negative, ovoid to rod-shaped bacteria that is phototrophic. All species use ammonia as a nitrogen source. Some strains are found only in sulfide-containing freshwater habitats exposed to light while others may occur in marine, estuarine, and freshwater environments.

**Tree numbers:** - B03.440.425.410.290 - B03.660.250.110.150