Photorhabdus luminescens

Photorhabdus luminescens (formally Xenorhabdus luminescens) is a Gammaproteobacteria, belonging to the family Enterobacteriaceae, and is a symbiotic pathogen of insects.

It lives in the gut of an entomopathogenic nematode of the family Heterorhabditidae. When the nematode infects an insect, P. luminescens is released into the blood stream and rapidly kills the insect host (within 48 hours) by producing toxins such as TcA. It also secretes enzymes which break down the body of the infected insect and bioconvert it into nutrients which can be utilised by both nematode and bacteria. In this way, both organisms gain enough nutrients to replicate (or reproduce in the case of the nematode) several times. The bacteria enter the nematode progeny as they develop. P. luminescens also secretes antibiotics to protect against competition from other bacteria.

P. luminescens is bioluminescent, however the purpose of this is not yet properly understood. Infection by this bacteria of the wounds of soldiers in the American Civil War caused the wounds to glow; this aided the survival of the soldiers due to the production of antibiotics by P. luminescens.