Abstract

A Streptomyces sp. strain named 5K10, isolated from soil samples of Kaziranga National Park, Assam, India was found to secrete an antimicrobial proteinaceous compound, showing in vitro antagonistic effect against some pathogenic bacteria, yeasts, dermatophytes and filamentous fungi. Capacity to produce extracellular antimicrobial substances by the strain 5K10 was assessed by conventional spot inoculation method in agar media against test microorganisms as well as fungal spore germination inhibition assay by microscopic observations. The fermented culture broth with ammonium sulfate precipitation revealed a biologically active proteinaceous compound and molecular weight estimated to be about 14.3 kDa on SDS-PAGE gel. Using Candida albicans MTCC 227 as the indicator strain, antagonistic activity of the proteinaceous compound in the region of the SDS-PAGE gel was confirmed. Bioactivity of the extracellular protein was sensitive to proteinases and partially susceptible to prolonged heat treatment. The results suggest that Streptomyces sp. 5K10 might be an important bioresource of lead molecules for developing antimicrobial agents to control bacterial and fungal infections.

Key words: Antifungal activity, extracellular protein, dermatophytes, Streptomyces.