Isolation and Identification of Photorhabdus Luminescens an Insect Pathogenic Bacteria Associated with Entomopathogenic Nematode

Photorhabdus luminescens is a gram negative symbiotic bacterium belonging to the family Enterobacteriaceae, and is a lethal pathogen of insects. It lives in the gut of an entomopathogenic nematode of the family Heterorhabditidae. When the nematode infects an insect, P. luminescensis released into the blood stream and rapidly kills the insect host by producing toxins. So the present study was carried out to isolate and characterize the bacterium Photorhabdus luminescens from entomopathogenic nematodes Heterorhabditis indica (Karnataka strain) collected from soils of V C farm Mandya (Karnataka agroclimatic Zone-6), Karnataka, India. A total of twenty nematodes were isolated from 30 soil samples by the use of 300 modified Galleria traps. The bacterium was isolated by streaking the heamolymph of the dead larva of Galleria on NBTA plates. The identification and characterization of the isolates was done by microscopic observation, biochemical and physiological characters like Gelatin liquefaction test, Catalase test, Lactose fermentation test, Urease test and Colony morphology studies on Nutrient agar, NBTA and Mac Conkey agar media. A total of eleven strains were characterized as P. luminescens and their molecular diversity analysis was done using Random Amplified Polymorphic DNA (RAPD) markers.