OPTIMIZATION OF ANTIFUNGAL COMPOUND PRODUCTION BY A MODERATELY HALOPHILIC STREPTOMYCES WERRAENSIS HB-11

A moderately halophilic strain of actinomycete HB-11, having ability to produce antifungal compound was isolated from soil samples collected from the region of Mumbai sea port, India. The strain HB-11 was identified as Streptomyces werraensis on the basis of its morphological characteristics and 16S rRNA gene sequencing. It is found to be active against both filamentous as well as yeast fungi including Aspergillus parasiticus, Aspergillus niger, Aspergillus flavus, Ustilago maydis, Helminthosporium gramineum, Alternaria solani, Mucor liomelis, Rhizopus oryzae, Sclerotium rolfsii, Fusarium moniliforme, Fusarium oxysporum and Candida albicans. The cultural conditions for the production of antifungal metabolite were optimized by using various parameters and using U. maydis as indicator test strain. The antifungal metabolite was extracted with organic solvents, purified by column chromatography and its polyene nature was determined by Ergosterol plate assay. The optimization studies for antifungal compound production revealed that the suitable period of incubation as 8 days, pH as 8.0, salinity (5%), starch and ammonium sulphate as suitable carbon and nitrogen sources respectively and presence of magnesium sulphate at 25mM in soybean casein digest broth