Aims: To investigate the feasibility of applying sorbent material X-Oil in marine oil spill mitigation and to survey the interactions of oil, acteria and sorbent. Methods and Results: In a series of microcosms, 25 different treatments including nutrient amendment, bioaugmentation with Alcanivorax borkumensis and application of sorbent were tested. Microbial community dynamics were analysed by DNA fingerprinting methods, RISA and DGGE. Results of this study showed that the microbial communities in microcosms with highly active biodegradation were strongly selected in favour of A. borkumensis. Oxygen consumption measurements in microcosms and gas chromatography of oil samples indicated the fast and intense depletion of linear alkanes as well as high oxygen consumption within 1 week followed by consequent slower degradation of branched and polyaromatic hydrocarbons. Conclusion: Under given conditions, A. borkumensis was an essential organism for iodegradation, dominating the biofilm microbial community formation and was the reason of emulsification. Significance and Impact of the Study: This study strongly emphasizes the pivotal importance of A. borkumensis as an essential organism in the initial steps of marine hydrocarbon degradation. Interaction with the sorbent material X-Oil® proved to be neutral to beneficial for biodegradation and also promoted the growth of yet unknown micro-organisms. © 2009 The Society for Applied Microbiology.