Determination the optimal conditions for the production of antibiotics from some species of Streptomyces bacteria that locally isolated

Abstract

The current study was conducted in the postgraduate laboratories of Education College for Pure Sciences at Tikrit-University for the period from the first of December 2019 until the end of March 2020. The study aimed to isolate and identify Streptomyces spp. from soil and optimize cultural growth conditions for Antibacterial Metabolites (including antibiotic) Production. Thirteen soil samples were collected from different locations in Tikrit city, Iraq ,Twenty-eight Streptomyces isolates were purified and testing their antibacterial activity using primary screening against pathogenic bacteria by perpendicular streaking method and the result showed that all isolates had antibacterial activity in different spectra. The active Streptomyces A11 isolate witch exhibited high activity against pathogenic bacteria was identified using several morphological and biochemical methods. Moreover, 16srRNA gene analysis confirmed that this isolate shbowed 99% identity to Streptomyces vinaceusdrappus. Ethyl acetate was used to extract the antibacterial compound from fermentation medium, the optimum growth conditions for antibacterial metabolite production by Streptomyces A11 isolates were incubation period in 6 days, pH 8 and temperature at 30°C. the GC-MS analysis revealed 12 chemical compounds that may have biological activity