Optimization of the Production of Biosurfactant From Iranian Indigenous Bacteria for the Reduction of Surface Tension and Enhanced Oil Recovery

The optimum conditions for biosurfactant production by Iran's isolates were examined. The Taguchi method was used to identify nutritional requirements in the medium using four parameters; that is, carbon source, nitrogen, phosphorous, and salt concentrations. The use of whey, oil, and sucrose as carbon sources; NaCl as salt source; (Na2HPO4, NaH2PO4) as phosphorous source; and (NH4)2SO4 as nitrogen source was examined to determine bacteria optimum conditions. According to the Taguchi method using the sucrose source, the optimal conditions for Bacillus subtilis were 50 g/L NaCl, 13.53 g/L (Na2HPO4, NaH2PO4), and 1 g/L (NH4)2SO4; for Bacillus cereus they were 25 g/L NaCl, 13.53 g/L (Na2HPO4, NaH2PO4), and 1 g/L (NH4)2SO4; and for Pseudomonas putida they were 25 g/L NaCl, 13.53 g/L (Na2HPO4, NaH2PO4), and 1 g/L (NH42SO. Oil displacement experiments in the micromodel at optimum conditions showed around 25% recovery of residual oil with added supernatant of Bacillus subtilis.