PTT Research and Technology Institute,Thailand
Suwat Soonglerdsongpha has completed his PhD from The University of Tokyo (Japan) in 2010. Currently, he is researcher at Environmental Research and Management Department, PTT Research and Technology Institute, PTT Public Company Limited (Thailand). His research is now focused on production and application of biosurfactant for petroleum and petrochemical industries and development of recombinant bacteria as bioreporter for environmental pollution monitoring.
Oil spill occurs frequently around the world during petroleum exploitation and transportation. Various chemicals have been used to disperse the oil into small droplets, which can stimulate oil biodegradation in the seawater. These dispersants are usually petroleum-based surfactants; which can be toxic and accumulated in the environment. Consequently, the demand of “green” and non-toxic dispersants for oil spill remediation is increasing. This research aimed to develop a lipopeptide-based dispersant from Bacillus sp. GY19, a biosurfactant producing bacterium. The production of lipopeptides was carried out by culturing Bacillus sp. GY19 in a stirred tank reactor containing palm oil-glycerol based medium. To recover lipopeptides from culture medium, a simple foam fractionation unit was used. The foamate from this process contained up to 11 g/L lipopeptides. To further concentrate the lipopeptides, the foamate was freeze-drying to give powder with 50% lipopeptides. These production processes eliminated the use of solvent in downstream process. The lowest surface tension of lipopeptide products was 26mN/m. Oil displacement test was used to represent oil dispersing activity of lipopeptides in seawater. The results showed that 1-3% lipopeptide solutions had 80-100% oil displacement efficiency with Oman light oil, heavy oil, diesel oil and Arabian light oil. The activities were comparable to a commercial dispersant (Slickgone NS) and much higher than a synthetic surfactant (Tween 20). In addition, the lipopeptide solutions were stable at extreme salinity, pH, and temperature. Consequently, foamate and powder containing lipopeptides could be used directly as dispersants for oil spill remediation.