Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Microbiology

In this work, five strains of Photorhabdus luminescence isolated from a local nematode strains namely Heterorhabditis indica (EGAZ1), H. indica (EGAZ2), H. indica (EGAZ3), H. indica (EGAZ4), H. indica (EGAZ5). In addition to a second bacterial symbiont Providencia rettgeri of H indica (EGAZ3), Photorhabdus luminescens subsp. laumondii HP88 which was isolated from Heterorhabditis bacteriophora (HP88), and Xenorhabdus nematophilus isolated from the hemolymph of Galleria mellonella infected with Steinernema carpocapsae (BA2). The identity of the isolated bacteria were authenticated referring to their cultural, morphological and biochemical traits as well as to their entomopathogenicity against Galleria mellonella. The 16S r RNA gene sequence technique was adopted for conclusive identification of the five isolates. Lab and pots experiments conducted to examine antimycotic activities of cell-free culture filtrates with different concentrations against plant pathogenic fungi Fusarium oxysporum, Fusraium solani, and Schloritium rolfsii, also the nematicidal activities of the bacterial cell suspensions and cell-free culture filtrates with different concentrations against Meloidogyne incognit were studied and larvae toxicity of the bacterial cell suspensions and cell-free culture filtrates with different concentrations pointed out to moderate susceptibility of T. absoluta larvae to all bacterial cell suspensions as well as their toxins

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