bioluminescent bacteria

Bioluminescent bacteria are any light-producing bacteria, present mostly in sea water, marine sediments, surface of decomposing fish and in gut of marine animals. These bacteria may live free (example, Vibrio harveyi) or in symbiosis (example, Vibrio fischeri) with animals such as the Hawaiian Bobtail squid or terrestrial nematodes (example, Photorhabdus luminescens). The animals provide these bacteria a safe home and sufficient nutrition and use the light organs for camouflage, preying for food and attracting mates. The bacteria may deploy luminescence reaction for quorum sensing - ability to regulate gene expression in response to bacterial cell density.