Studies on medium optimization for the production of antifungal and antibacterial antibiotics from a bioactive soil actinomycete

A microbial isolate, characterized as Streptomyces sp. (MTCC 6819), produced antifungal metabolite intracellularly and antibacterial metabolite extracellularly under submerged fermentation conditions. This Gram-positive bacterium showed broad antimicrobial activity spectra against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) of partially purified (68.4%) antibacterial metabolite ranged between 50 and 12.5 μg/mL against multiple-drug-resistant bacteria. The producer organism exhibited strong activity against various yeast and fungi. The MIC values of the partially purified (70%) antifungal metabolite ranged between 6.25 and 3.125 μg/mL for unicellular fungi and 12.5 and 6.25 μg/mL for filamentous fungi. The conditions for the production of these bioactive agents were optimized and the effects of various nutritional factors were studied by classical and statistical methods.