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

It is known that marine invertebrates, including sponges, soft corals and hard coralshost various communities of symbiotic microorganisms. These microorganisms associated with the invertebrates metabolized various biologically active compounds, which have different activities. This study aims to isolate sponge and soft coral associated bacteria from Red Sea, and to determine the potential antibacterial activity of bacterial isolates and detection of PKS and NRPS gene clusters which are involved in the production of bioactive secondary metabolites. Fifty four bacterial isolates were isolated from five sponge and five soft coral samples from different Red Sea areas. These isolates were tested for their possible antibacterialactivity against Gram positive bacteria (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633) and Gram negative bacteria (Escherichia coli ATCC 25922,) and yeast (Candida albicans ATCC 10231) using the well diffusion method. Six isolates showed different antibacterial activity against different bacteria and yeast. These isolates were identified molecularly through 16 rRNA which showedthe diversity of sponge and soft coral associated bacteria, and these six isolates were tested for the presence of PKS and NPRS using five primers.One isolate showed the presence of the five genes, two isolates showed the presence of 4 genes, one isolate showed the presence of three genes, one isolate showed the presence of one gene, and only one isolate was negative for the presence of any of the five genes

Issued also as CD