Abstract
The present study was aimed at molecular and phenotypic characterization of two new bacterial strains isolated from entomopathogenic nematodes, Heterorhabditis indica RM1 from Alexandria, northern Egypt and Heterorhabditis sp. S1 from RasSidr, South Sinai, eastern Egypt. These entomopathogenic bacteria secrete lethal toxins that rapidly kill the insect host within 48h. They also produce various antibiotics that suppress infection by other microorganisms. Three complementary approaches including16S rRNA gene sequencing, phenotypic and phylogenetic analysis by maximum likelihood method and chemical characterization, were used to identify these new isolates. Current investigations revealed that these two isolates had noteworthy differences, particularly in their antibiotic production spectrum from P. luminescens subsp. akhurstii 1S5; however, they maintain the major characters that define them from other species. A minor difference from regular P. luminescens subsp. akhurstii was obtained by 16S rRNA gene sequencing, which resulted in two new type strains: Photorhabdus luminescens subsp. akhurstii HRM1KC237382 and Photorhabdus luminescens subsp. akhurstii HS1KC237383.