Abstract | Streptomyces sp. MNK7 was isolated from Natore, Bangladesh. Morphological, physiological and biochemical studies strongly suggested that the isolate belonged to Streptomyces. Attempts were made to optimize the culture conditions for the production of antimicrobial metabolite by this strain. Antimicrobial metabolite production was started after 3 days of incubation and maximum level was obtained after 10 days and thereafter gradually decreased. The optimum temperature and pH for antimicrobial metabolite production was 35oC and 5 respectively. Inositol and L-Asparagine as carbon and nitrogen sources was proved to be the best for production of bioactive metabolite. The extract of metabolite was obtained by solvent extraction method using ethyl acetate as the solvent. The ethyl acetate extract exhibited reasonable antibacterial activities against a series of Gram positive and Gram negative bacteria. The minimum inhibitory concentrations (MICs) of crude extract were found to be in the range of 32-64 mg/ml against seven pathogenic bacteria. The extract also assessed for preliminary cytotoxicity and the LC50 values were found to be 7.58 μg/ml. |
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