Production and partial characterization of biosurfactant produced by crude oil degrading bacteria

Production of biosurfactant by crude oil degrading bacteria for use in microbial enhanced oil recovery was investigated. Crude oil utilizing bacteria were isolated from soil by enrichment method on oil agar at 30 °C for 5 days. The isolates were identified and screened for biosurfactant production using blood haemolysis and emulsification tests. IR and GC–MS analyses were carried out to detect the type of biosurfactant. The biosurfactant was purified and its stability at various pH, temperature and salinity levels was studied. The organisms were identified as: Achromobacter xylosoxidans subspecies xylosoxidans, Bacillus licheniformis, Proteus vulgaris, Proteus mirabilis, Serratia marcescens, Sphingomonas paucimobilis and Micrococcus kristinae. Emulsification test (E24) revealed that Serratia marcescens had the highest emulsification index of 87%. GC–MS indicated the biosurfactants as lipopeptides. The biosurfactant can be used in EOR under various environmental conditions.

► Bacteria identified in this study were active crude oil degraders and biosurfactant producers.
► Serratia marcescens was the most potent biosurfactant producer mainly, lipopeptide with high emulsification index (87%).
► The biosurfactant is apparently a new type of lipopeptide.
► The biosurfactant had high emulsification activity and exhibited stability in a wide range of pH, temperature and salinity.
► Sand pack column experiment revealed the potential of the biosurfactant to be used for EOR.