Simple Summary:Bacteria from the genus Photorhabdus and Xenorhabdus are found in symbiotic association with entomopathogenic nematodes of the family Heterorhabditidae and Steinernematidae, respectively. These nematodes are used with limited success as an effective biological control against insect pests of the order Coleoptera and Lepidoptera, including white grubs, weevils, and codling moths, the typical workflow of (Photorhabdus and Xenorhabdus) form a promising bacterial source of non-ribosomal peptides and it is a great fortune for natural products scientists and microbiologists that bacteria can also be cultivated without their host in the laboratory which could be a perfect bio-control agent against important agricultural insects.
            Two symbiotic association bacteria isolated from the Galleria mellonella larval hemolymph were identified by 16s rDNA as Photorhabdus PMG05 and Xenorhabdus XMG01 with accessions numbers of MZ733679 and MZ733678, respectively. The GC-MS analysis for the purified culture of Photorhabdus luminescens PMG05 and Xenorhabdus nematophila XMG01 bacteria revealed several PKS-NRPs syntheses molecules. The main constituents were Piperidinone (44.09%) and Pyrrolidinone (35.04%) for Photorhabdus and Xenorhabdus, respectively.The presence of NRPS genes in identified bacteria was detected in four sets of degenerate primers. The degenerate primers of the first set amplified fragments with both strains, while those degenerate primers of the second and third sets amplified only fragments of Photorhabdus strain, whereas no fragments were detected with the fourth set. predicted bioactivity step for either antioxidant or antimicrobial for the generated peptides by the NRPSs of the two studied organisms, two antimicrobial predictors show high scores for the abovementioned peptides of the Photorhabdus luminescens. However, the Peptide Ranker alone scores a high antimicrobial activity for the same peptide with the moderate antioxidant activity of Xenorhabdus nematophila.