In this study, thirty Streptomyces strains were isolated from macroalgae around the Euphrates river by spread plate method as well as to optimize cultural growth conditions for maximum antibacterial productivity. The colonies were purified by repeated streak on an international Streptomyces project-2 (ISP-2) medium subculture plate for active strain. The antibiotic susceptibility profile showed resistance to most of the antibiotics tested. By using the cross streak method and the agar well diffusion method, twelve isolates were screened for antagonistic activity against four different human pathogenic bacterial strains. One strain (Streptomycessp. AS5) was found to be more active against biofilm-producing bacteria (Klebsiella pneumonia and Escherichia coli). The strain was identified by 16S rRNA partial gene sequencing. The antibacterial and antibiofilm compounds produced by Streptomyces sp. AS5 was identified by using GC-MS report as Pyrrolo [1, 2-a] pyrazine-1,4-dione, hexahydro-. It is concluded that Streptomycessp. AS5 that isolated from macroalgae is a promising source of antibacterial and antibiofilm secondary metabolites against human bacteria species.
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