Microbial communities play a crucial role in microbial loop process that constitute the foundation of the ecosystem structure and function. The goal of this study was to monitor microbial community shift in the Gulf of Mexico coastal sediments following exposure to MC252 oil in a laboratory microcosm experiment. We used bacterial tag encoded FLX pyrosequencing (bTEFAP) approach targeting the 16S rRNA gene. We also studied the presence of the biodegradative genes in pure cultures of bacteria from oil-treated sediments samples.