Luminous Bacteria

(or photobacteria), bacteria that emit light. A blue-green luminescence with a wave length of 410–650 nanometers is observed in rodlike or coiled bacteria belonging to the genera Photobacterium, Lucibacterium, and Vibrio. The luminescence is dependent on the presence of the enzyme lucifer-ase in the cells of these bacteria and is observed only in the presence of free oxygen. Luminous bacteria are found in the surface layer of seawater. Some species of these bacteria are symbionts of cephalopod mollusks and fish and accumulate in their luminescence organs. Together with other luminescent organisms, luminous bacteria cause phosphorescence of the sea. The term “photobacteria” is sometimes applied improperly to photo-synthesizing bacteria.