title: Biosurfactant production under extreme environmental conditions by an efficient microbial consortium, ERCPPI-2.
abstract: The biosurfactant production potential of a new microbial consortium of Enterobacter cloacae and Pseudomonas sp. (ERCPPI-2) which was isolated from heavy crude oil-contaminated soil in the south of Iran, has been investigated under extreme environmental conditions. The isolated consortium produces a biosurfactant mixture with excessive oil spreading and emulsification properties. This consortium was able to grow and produce biosurfactant at temperatures up to 70 °C, pressures up to 6000 psia, salinities up to 15% (w/v), and in the pH range 4-10. Besides, the optimum biosurfactant production conditions were found to be 40 °C and 7.0 for the temperature and pH value, respectively. These conditions gave the best biosurfactant production of 1.74 g/1 when the cells were grown on a minimal salt medium containing 1.0% (w/v) olive oil, 1.0% (w/v) sodium nitrate supplemented with 1.39% (w/v) K(2)HPO(4) at 40 °C and 150 rpm after 48 h of incubation. The ERCPPI-2 could reduce surface and interfacial tensions to 31.7 and 0.65 mN/m from the original values of 58.3 and 16.9 mN/m, respectively. The isolated consortium produced biosurfactant using heavy crude oil as the sole source of carbon and emulsified the available heavy crude oil up to E(24)=83.4%. The results of the core holder flooding tests at simulated reservoir conditions demonstrated that the oil recovery efficiency due to the injection of the cell-free biosurfactant solution was 27.2%, and the bacterium injection reduced the final residual oil saturations to below 3% at optimum conditions.
authors.affiliation: School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran.
authors.forename: Parviz
authors.initials: P
authors.lastname: Darvishi
authors.forename: Shahab
authors.initials: S
authors.lastname: Ayatollahi
authors.forename: Dariush
authors.initials: D
authors.lastname: Mowla
authors.forename: Ali
authors.initials: A
authors.lastname: Niazi
mesh_terms: D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D059013:Microbial Consortia; D010578:Petroleum / Q000382:microbiology; D012988:Soil Microbiology; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
chemical_list: D010578:Petroleum; D013501:Surface-Active Agents