batch_auto_20260713 202607131256465730 BOEM ESP geoESPIS ESPIS@boem.gov Bureau of Ocean Energy Management Microbial Biodegradation of Alaska North Slope Crude Oil in the Arctic Marine Environment Institute of Arctic Biology University of Alaska Fairbanks This project investigated the biodegradation of Alaska North Slope crude oil and Corexit 9500 (Corexit) in Arctic seawater and sediments to identify the microbes and genes actively involved in the biodegradation process. Results showed degradation of non-ionic surfactants in Corexit occurred before biotic degradation of petroleum hydrocarbons, but Corexit did not suppress oil biodegradation. The presence of oil appeared to delay mineralization of the Corexit component dioctyl sodium sulfosuccinate (DOSS). Some taxa responded selectively to the presence of oil (Thalassolituus, Sedimentalea) or Corexit (Colwellia, Polaribacter, Moritella, Octadecabacter, and Amylibacter); other taxa (Oleispira, Pseudofulvibacter, and Roseobacter) responded to both, suggesting the ability to utilize compounds from oil and Corexit. Metatranscriptomics (gene expression) analyses of experimental seawater microbial communities revealed that oil and Corexit stimulated different metabolic gene expression profiles in the microbial community. 174931 U.S. Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program https://doi.org/10.13039/100012475 M17AC00005 10.67297/9A1DEF https://boem.gov/awardpages/100207