Comparative Study of Biosurfactant Producing Organisms Isolated from Pesticide and Oil Contaminated Soil

Abstract

Biosurfactants are diverse groups of surface active molecules synthesized by microorganisms which help in stabilizing emulsion, enhancing foaming and reducing surface tension. In this study, six soil samples were collected from pesticide and oil contaminated sites. Each sample was enriched in mineral salt medium then serially diluted and pour plated in the nutrient agar plates. A total of 32 morphologically distinct isolates were isolated in pure form from soil samples which were screened for the purpose of biosurfactant production. To confirm and compare the ability of isolates in biosurfactant production from different sources, different screening methods including foaming, emulsification index E24, drop collapse method and oil spreading test were assessed. Curd whey was used as a low cost growth medium for biosurfactant producing organisms. Kocuria rosea from pesticide contaminated soil and Micrococcus luteus/ lylae from oil contaminated soil sample were potent biosurfactant producers which were furthermore identified. Kocuria rosea showed highest emulsification index and prominent zone for oil spreading assay as compared to Micrococcus luteus/ lylae which suggested that biosurfactant producers isolated from pesticide contaminated soil sample have higher potency than biosurfactant producers isolated from oil contaminated soil sample.