Photorhabdus

Photorhabdus is a genus of bioluminescent, gram-negative bacilli which lives symbiotically within entomopathogenic nematodes, hence the name photo (which means light producing) and rhabdus (rod shape).

During stationary phase growth inside insect larvae, Photorhabdus species synthesize a molecule called 3,5-Dihydroxy-4-isopropyl-trans-stilbene (ST).

It is proposed that ST acts as an antibiotic and protects Photorhabdus species from competition from other microorganisms, and also helps circumvent the insect's immune system.

[3] Another important sequence identified is the gene encoding polyketide and nonribosomal peptide syntheses which produce antibiotics to protect against microbial competitors.

Use of Photorhabdus species alone as biopesticide, independent of its nematode symbiont, against the cabbage white butterfly, Pieris brassicae, mango mealy bug, Drosicha mangiferae and the pupae of the diamond back moth, Plutella xylostella has been demonstrated successful.