Optimization of Conditions and in Vitro Antibacterial Activity of Secondary Metabolite Isolated from Streptomyces sp. MNK7

Abstract

Streptomyces sp. MNK7 was isolated f rom 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 pr oduction was started af ter 3 day s of incubation an d m aximum level was obtained after 10 days and t hereafter gradually decreased. The optimum t emperature and pH for antimicrobial metabolite production was 35°C 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 o btained by so lvent ex traction method using ethyl acetate as the solvent. The ethyl acetate extract exhibited reasonable ant ibacterial activities agai nst a s eries of Gram positive and Gram negative bacteria. The m inimum inhibitory concentrations (MICs) of c rude extract were found to be in t he range of 3 2-64 mg/ml ag ainst se ven pathogenic bacteria. T he extract also assessed for p reliminary c ytotoxicity 50 and the LC values w ere found to be 7.58 µg/ml.