Optimization of culture conditions for antimicrobial metabolites production by Streptomyces sp. against bacterial leaf blight pathogen Xanthomonas oryzae pv. oryzae

Abstract

An investigation was conducted to explore the antimicrobial potential of Streptomyces sp. TC1 against Xanthomonas oryzae pv. oryzae (Xoo) which causes bacterial leaf blight disease in rice. The TC1 strain was found to produce maximum antimicrobial metabolites upto 7 days in starch casein broth. The starch and yeast extract positively influences the antimicrobial metabolites production. The produced antimicrobial metabolites in modified starch casein broth were extracted using ethyl acetate and the pH of broth adjusted to 3 prior to extraction process for the better recovery of antimicrobial metabolites. The ethyl acetate crude extract possess an MIC of 300 µg/mL and IC50 value of 125 µg/mL against the test pathogen Xoo. The culture filtrate and crude extract of TC1 strain also showed antimicrobial activity against various isolates of Xoo.