Bio-dispersant produced by a Rhodococcus erythropolis mutant as an oil spill response
Bio-dispersants have been considered as superior alternatives of currently used dispersants as they are generally more biodegradable, less toxic, and better at enhancing biodegradation. However, the application of bio-dispersants is limited by the availability of economic products and the corresponding producers that can work effectively. Hyperproducers generated by metabolic engineering of biosurfactant producers are highly desired to overcome this obstacle. A Rhodococcus erythropolis SB-1A strain was isolated from Newfoundland offshore oily water samples. One of its mutant derived by random mutagenesis with ultraviolet radiation, producing high levels of biosurfactants was selected by the oil spreading technique. The mutant produces biosurfactants with critical micelle dilutions (CMD) approximately 4 times of the parent strain. The results obtained with thin layer chromatography (TLC) indicated the produced biosurfactant remained unchanged between the mutant and the parent strain. In addition, the produced biosurfactants were recovered with solvent extraction method and applied as the oil spill response agents to effectively disperse oil slick. Based on the baffled flask test (BFT) results, the dispersion efficiency of the biosurfactants produced by the mutant is higher than that induced by the parent strain and Corexit 9527 while comparable to the Corexit 9500.