Antibacterial and anti-HIV activity of extracellular pigment from Streptomyces sp. S45 isolated from Sabarimala forest soil, India

Abstract

Actinobacteria, particularly from under-studied habitats, are often endowed with diverse biological properties. In the present study, about 17 actinobacterial strains were isolated from Sabarimala forest an understudied ecosystem in Western Ghats, India and screened for their pigment producing potential. Pinkish brown soluble pigment producing Streptomyces sp. strain S45 was selected and screened for antibacterial and anti-HIV activity. The bioactivity of ethyl acetate extract of the strain S45 showed maximum zone of inhibition against Staphylococcus aureus ATCC 29213 (17.3±0.4 mm) and Bacillus cereus (15.6±0.6 mm). Also, it showed anti-HIV activity with the IC50 value of 8.75 µg/mL. The bioactive pigment isolated from the strain S45 was partially purified and characterized using UV absorption. In bio-autography, an antibacterial compound found to be active against S. aureus ATCC 29213 and its MIC values ranged between 25-1.56 µg/mL. Variables such as glucose, rhamnose, soybean meal and CaCl₂, pH 7 and temperature 30℃ were found to influence bioactive pigment production. Potential strain S45 was identified as Streptomyces species on the basis of microscopic, cultural, physiological and 16SrRNA analysis. Results suggest that the Streptomyces sp. S45 strain explored in this study could be a promising candidate for isolation of antibacterial and anti HIV pigment.