Isolation of biosurfactant producing bacteria from Potwar oil fields: Effect of non-fossil fuel based carbon sources

Abstract

Biosurfactants are surface-active metabolites produced by microorganisms. Biosurfactants tend to solubilize hydrocarbons in the surrounding environment, by reducing surface tension and increasing carbon uptake. In this study, isolation of biosurfactant producing bacteria and effect of renewable, non-fossil fuel based carbon sources on production were assessed. Oil field produced water was collected from Potwar oil fields and thirteen strains were isolated. Strains were screened for biosurfactant production by hemolysis test, emulsification index test, emulsification assay, oil displacement test, drop collapse test, tilted glass slide test and oil coated agar emulsification test. Strains were further screened for maximum production on cost effective renewable carbon source e.g. glucose, waste glycerol and animal fat. Promising strains were identified as Bacillus subtilis (MH142143), Pseudomonas aeruginosa (MH142144), Bacillus tequilensis (MH142145) and Bacillus safensis (MH142146) by 16S rRNA gene sequencing. Among all isolates, highest biosurfactant production on glucose (37%), glycerol (48%) and animal fat oil (49%), after 24 h cultivation was by Pseudomonas aeruginosa. Biosurfactant showed similarity to rhamnolipids by Thin Layer Chromatography (TLC). Assessment of bioactive propertiaes of rhamnolipid showed strong antimicrobial activity against Bacillus spp. Future investigations can be focused on application of these strains in environmental as well as industrial sectors.