The contribution of chemical dispersants and biosurfactants on crude oil biodegradation by Pseudomonas sp. LSH-7′

Abstract The application of surfactants as dispersants for the remediation of contamination by a variety of petroleum hydrocarbons has received much attention from researchers worldwide because petroleum hydrocarbons may cause great potential harm to the marine environment and human health. A simulated bioremediation of a marine offshore oil spill was carried out to determine the contribution of chemical dispersants and biosurfactants on bioremediation of Haierzhan crude oil. Compared to chemical dispersants, biosurfactants were more effective at bioremediation of oil-contaminated marine environment. Rhamnolipids did enhance the bioremediation of petroleum hydrocarbon compounds with a coefficient of 9.02 using the RSM equation, which is much higher than a coefficient of 4.42 observed with the commercial chemical dispersants GM-2. There was a synergistic effect between Dioctyl Sodium Sulfosuccinate (DOSS) and GM-2 on the bioremediation of crude oil, with the coefficient for the two factors being 16.58, while, the contribution of rhamnolipid with GM-2 resulted in a negative effect on crude oil biodegradation, with a coefficient −7.72. The strain LSH-7′ grew very well when the medium were amended with biosurfactants as the sole carbon source, indicating that the biosurfactants have no toxic effect on the hydrocarbon-degrading microorganisms.