Studies on bioemulsifier production from marine Streptomyces sp. S1

Abstract

Out of the 80 strains of actinomycetes isolated and screened from Alibag, Janjira and Goa coastal regions of India, 56 showed lipase activity. Six potential strains were studied for bioemulsifier production by using oils and hydrocarbons as substrates. Streptomyces sp. S1 isolated from Goa showed maximum bioemulsifier production of 200 EU/mL. It also showed significant growth on maltose yeast extract medium. The fermentation conditions were optimized. Maximum bioemulsifier production was obtained at an initial pH 7, temperature 28ºC, 120 rpm, sodium chloride concentration 3% (w/v) and time 14 d. Bioemulsification activity was significant against growth media containing 1% (v/v) toluene (361.2 EU/mL). A medium containing 1% (v/v) toluene showed appreciable reduction in surface tension (42.6 dynes/cm). Critical micelle concentration (CMC) of purified composite bioemulsifier was 0.3 mg/mL. The bioemulsifier having 82% protein, 17% polysaccharide and 1% reducing sugar was unstable at 10 and 50ºC; but was found to be stable at room temperature (28ºC). The optimized fermentation process produced a bioemulsifier yield of 3.8 g/L.