The bacterial symbionts IRQ.1 and IRQ.2 were isolated from populations of the insect pathogenic nematode Heterorhabditis bacteriophora collected from Iraq. These bacteria were symbiotically associated with entomopathogenic nematodes of genus Heterorhabditis, contributing actively to the biological cycle of their host. The Heterorhabditidae family of nematodes involves of obligate insect pathogens. Both the nematode and bacteria work together to overcome the immune response of target insect. The bacteria were isolated from crushed number of infective juveniles. On the indicator NBTA plates, characteristic blue colonies of Photorhabdus were developed slowly, then, the colony was picked from isolation plates only after 48 h. This study was based on phylogenetic analysis of sequence data of two genes: 16S rRNA and gyrB. The bacteria were also characterized phenotypically by biochemical and physiological tests. Our results have shown that the Photorhabdus strains isolated from H. bacteriophora belong to Photorhabdus luminescens subsp. akhurstii. This is indeed the case for the strain examined in this study which has been isolated from the recently described H. bacteriophora from Iraqi soil.

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