Production and Application of Gordonia westfalica GY40 Biosurfactant for Remediation of Fuel Oil Spill

Abstract

This study aims to produce and apply a biosurfactant from Gordonia westfalica GY40 for enhancing fuel oil solubilization and degradation in seawater. The immobilization of G. westfalica GY40 cells on chitosan flakes increased biosurfactant yield, and we achieved a biosurfactant concentration as high as 1.85 g L−1 when using 2 % soybean oil as the carbon source. The critical micelle dilution (CMD) value of cell-free broth was 25 % and the lowest surface tension was 35 mN m−1. The cell-free broth was able to solubilize and disperse fuel oil, at efficiencies corresponding to biosurfactant concentrations and CMD values. The surface activity of cell-free broth was stable under wide ranges of salinity, temperature, and pH. For the oil degradation test, cell-free broth at 0.5× CMD was added along with polyurethane foam-immobilized Gordonia sp. JC11, an efficient oil-degrading bacterial inoculum, to fuel oil spiked seawater. The system removed 81 % of 1 g L−1 fuel oil in nutrient seawater medium within 6 days. When tested with three seawater samples collected along the Thai coastal area, the addition of both biosurfactant and immobilized Gordonia sp. JC11 was able to remove 60–70 % of 1 g L−1 fuel oil, while the natural attenuation (control) removed only 26–35 % of fuel oil. The application of cell-free broth reduced the extraction and purification steps. In addition, the simple production of G. westfalica GY40 biosurfactant and Gordonia sp. JC11 inoculum suggested that they are suitable for cleaning-up oil spills in seawater.