Janthinobacterium lividum is an aerobic, gram-negative, soil-dwelling bacterium that has a distinctive dark-violet (almost black) color. This color is due to a compound called violacein, which is produced when glycerol is metabolized as a carbon source. Violacein has anti-bacterial, anti-viral, and anti-fungal properties. Its anti-fungal properties are of particular interest since J. lividum is found on the skin of certain amphibians, including the red-backed salamander (Plethodon cinereus), where it prevents infection by the devastating chytrid fungus (Batrachochytrium dendrobatidis).
Growing black ink out of Janthinobacterium lividum
The genus name, Janthinobacterium, comes from Latin janthinus, which means "violet" or "violet-blue" + bacterium, which means rod or staff. The species name is also from Latin, lividum, which means "of a blue or leaden color".