Screening Microbial Surface Active Compound Produced by Bacteria Isolated from Various Waste Streams

Abstract

Microbial surface active compounds (SACs) have been studied for bioremediation of non-aqueous phase liquids (NAPLs) contaminated sites where SACs reduce the surface tension and therefore improve the bioavailability of NAPLs. Hence, this study evaluates presence of microbial SACs in culture medium by detecting the surface activity of potential SAC-producing bacteria. Twenty-five strains isolated from various waste streams in Malaysia were screened for SAC production by preliminary screening tests, namely using drop collapse, oil spreading and microplate tests. Strains were further checked using complementary screening by measuring the surface tension. Four strains (P-UT4, P-UT5, P-UT6 and P-UT8) isolated from untreated palm oil mill effluent (POME) exhibited high surface active properties when tested through preliminary screening tests. These strains were also capable of reducing surface tension of water (72 mNm-1) to below 40 mNm-1 and thus were identified as potential SAC-producing bacteria.