Effect of bioemulsificant exopolysaccharide (EPS2003) on microbial community dynamics during assays of oil spill bioremediation: A microcosm study

► EPS2003 can be applied as an oil spill remediation agent in marine environments. ► Presence of EPS2003 influence the quali-, quantitative composition of marine bacteria. ► EPS2003 favors the increment of hydrocarbonoclastic bacteria (e.g. Alcanivorax sp.). Microcosms experiments were carried out to evaluate the effect of bioemulsificant exopolysaccharide (EPS2003) on microbial community dynamics. An experimental seawater microcosm, supplemented with crude oil and EPS2003 (SW+OIL+EPS2003), was monitored for 15days and compared to control microcosm (only oil-polluted seawater, SW+OIL). Determination of bacterial abundance, heterotrophic cultivable and hydrocarbon-degrading bacteria were carried out during all experimentation period. The microbial community dynamic was monitored by isolation of total RNA, RT-PCR amplification of 16S rRNA, cloning and sequencing. Oil degradation was monitored by GC–MS analysis. Bioemulsificant addition stimulated an increase of the total bacterial abundance, change in the community structure and activity. The bioemulsificant also increased of 5 times the oil biodegradation rate. The data obtained from microcosm experiment indicated that EPS2003 could be used for the dispersion of oil slicks and could stimulate the selection of marine hydrocarbon degraders thus increasing bioremediation process.