Dodecanol-Modified Petroleum Hydrocarbon Degrading Bacteria for Oil Spill Remediation: Double Effect on Dispersion and Degradation

Effective emulsification of oil in seawater plays an important role in the marine oil spill remediation process. The negative effects of chemical surfactants have necessitated a search for alternative dispersant that are sustainable and environmentally friendly. After modifying with dodecanol, petroleum hydrocarbon degrading bacteria, Bacillus cereus S-1, was elucidated to produce an extremely stable oil-in-water (o/w) Pickering emulsion, just liking a solid particle emulsifier. In an appropriate concentration range, the presence of dodecanol improved the surface hydrophobicity and wettability of bacterial cells, which was responsible for their adsorption at the oil water interface. When a sufficient amount of bacteria was added, only a small amount of dodecanol was required to obtain stable emulsions. However, stable emulsion was not prepared with unmodified Bacillus cereus S-1 cells. Scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) images indicated that the effective emulsification was attributed to the formation of a dense bacterial interfacial film around oil drops, providing a steric barrier to impeding droplet coalescence. For application in emulsification of crude oil in seawater, the dodecanol-modified bacterial cells (DMB) were still very effective. In addition to emulsification, DMB remarkably facilitated the oil biodegradation compared to bacterial cells alone. By combining the emulsification and biodegradation of sustainable hydrocarbon degrading bacteria, this work showed a novel strategy for developing an alternative, environmentally friendly remediation technology for marine oil spills.