Chromobacterium violaceum is a motile, gram-negative bacillus. The organism is a common inhabitant of soil and water in tropical and subtropical regions. Occasionally, it can act as an opportunistic pathogen in animals and humans and the initial skin lesion can lead to multiple liver and lung abscesses and fatal septicemia. In most of these cases the route of entry was through the broken skin, following contamination with soil or water.
The organism produces a violet pigment called violacein, which gives the colonies a distinctive metallic, dark purple sheen. Violacein has been shown to exhibit important antitumor and antimicrobial properties. In addition to violacein, C. violaceum produces a number of natural antibiotics such as aerocyanidine.