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Abstract
Objective: The objective of this work was to isolate bacteria from Red Sea invertebrates, determine the antimicrobial activity of the bacterial extract, and screen for the biosynthetic gene clusters (PKS and NRPS) which could be involved in the production of bioactive secondary metabolites. Then, combining the bacterial extract with the antimicrobial polysaccharide chitosan nanoparticles and testing if the antimicrobial activity will be enhanced.Methods: Eleven different samples of Red Sea invertebrates were collected in Egyptian region and the associated microorganisms were cultivated and screened for the antimicrobial activity against five reference strains (Gram positive Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 9144, Gram-negative E.coli ATCC 10536 and Pseudomonas aeruginosa ATCC25619, and Candida albicans ATCC 90028).Then these isolates were screened for the presence of the biosynthetic genes PKS I&II and NRPS I&II. After that, the genes were cloned using (TOPO TA kit) and sequenced using Applied Biosystem. Finally, the structures of the secondary metabolite gene clusters in the genomes of isolate HHF-8 were predicted by The Natural Product Domain Seeker (NaPDoS) software.The second antimicrobial agent, chitosan nanoparticles were synthesized and combined with Bacillus amyloliquefaciens’s extract and characterized using Nanotrac wave II for particle size measurement. Finally, the antimicrobial activity was tested for the chitosan, the most potent isolate’s extract and chitosan-extract nanocomposite, against the five reference strains (Gram positive Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 9144, Gram-negative E.coli ATCC 10536 and Pseudomonas aeruginosa ATCC25619, and Candida albicans ATCC 90028)