Long-Term Combined Effects of Crude Oil and Dispersant on Sediment Bacterial Community

Abstract

To better understand long-term combined effects of crude oil and dispersant on bacterial community, sediments microcosms were set up in triplicates and treated with dispersant (Corexit 9500A), crude oil, and Corexit 9500A plus crude oil. After 60 days exposure, there was a significant change in the bacterial community structure in all treatments. The shift in the bacterial community structure in Corexit 9500A plus crude oil treatment was considerably different from those by either Corexit 9500A or crude oil. DNA sequence analysis showed that Hydrocarboniphaga effuse, Parvibaculum lavamentivorans,and Alicyclobacillus ferrooxydans were the major bacterial species in crude oil treatment. Pandoraea thiooxydans, Janthinobacterium sp. and Hyphomicrobium nitrativorans were the most dominant species in Corexit 9500A treatment. The species Janthinobacterium sp., Parvibaculum lavamentivorans, and Dyella sp. were enriched in Corexit 9500A plus crude oil treatment. The majority of the detected species were hydrocarbons degraders. The study showed that Corexit 9500A addition enhanced the biodegradation rate by increasing the diversity and richness of hydrocarbons degrading species. Corexit A9500 application should be considered during crude oil spills to evaluate environmental impacts.