Biosurfactant produced by a Rhodococcus erythropolis mutant as an oil spill response agent

Biosurfactants have been considered as superior alternatives to currently used surfactants as they are generally more biodegradable, less toxic, and better at enhancing biodegradation. However, the application of biosurfactants is limited by the availability of economic biosurfactants 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 offshore oily water samples. One of its mutants 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 approximately four times those of the parent strain. The results obtained with thin layer chromatography indicated the produced biosurfactant remained unchanged between the mutant and the parent strain. In addition, the produced biosurfactants were recovered with solvent extraction and applied as the oil spill response agents. 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. When compared with Corexit dispersants, it was found that the produced biosurfactants performed better than Corexit 9527 and were comparable with Corexit 9500.