Characterization of symbiotic and associated bacteria from entomopathogenic nematode Heterorhabditis sp. (nematode: Heterorhabditidae) isolated from India

Abstract Background Entomopathogenic nematodes (EPNs) harboring symbiotic bacteria are one of the safest alternatives to the chemical insecticides for the control of various insect pests. Infective juveniles of EPNs locate a target insect, enter through the openings, and reach the hemocoel, where they release the symbiotic bacteria and the target gets killed by the virulence factors of the bacteria. Photorhabdus with Heterorhabditis spp. are well documented; little is known about the associated bacteria. Main body In this study, we explored the presence of symbiotic and associated bacteria from Heterorhabditis sp. (IISR-EPN 09) and characterized by phenotypic, biochemical, and molecular approaches. Six bacterial isolates, belonging to four different genera, were recovered and identified as follows: Photorhabdus luminescens, one each strain of Providencia vermicola, Pseudomonas entomophila, Alcaligenes aquatilis, and two strains of Alcaligenes faecalis based on the phenotypic, biochemical criteria and the sequencing of 16S rRNA gene. Conclusion P. luminescens is symbiotically associated with Heterorhabditis sp. (IISR-EPN 09), whereas P. vermicola, P. entomophila, A. aquatilis, and A. faecalis are the associated bacteria. Further studies are needed to determine the exact role of the bacterial associates with the Heterorhabditis sp.