To advance understanding of the fate of hydrocarbons released from the Deepwater Horizon oil spill and deposited in marine sediments, this study characterized the microbial populations capable of anaerobic hydrocarbon degradation coupled with sulfate reduction in non-seep sediments of the northern Gulf of Mexico. Anaerobic, sediment-free enrichment cultures were obtained with either hexadecane or phenanthrene as sole carbon source and sulfate as a terminal electron acceptor. Phylogenetic analysis revealed that enriched microbial populations differed by hydrocarbon substrate, with abundant SSU rRNA gene amplicon sequences from hexadecane cultures showing high sequence identity (up to 98%) to Desulfatibacillum alkenivorans (family Desulfobacteraceae), while phenanthrene-enriched populations were most closely related to Desulfatiglans spp. (up to 95% sequence identity; family Desulfarculaceae). Assuming complete oxidation to CO2, observed stoichiometric ratios closely resembled the theoretical ratios of 12.25:1 for hexadecane and 8.25:1 for phenanthrene degradation coupled to sulfate reduction. Phenanthrene carboxylic acid was detected in the phenanthrene-degrading enrichment cultures, providing evidence to indicate carboxylation as an activation mechanism for phenanthrene degradation. Metagenome-assembled genomes (MAGs) revealed that phenanthrene degradation is likely mediated by novel genera or families of sulfate-reducing bacteria along with their fermentative syntrophic partners, and candidate genes linked to the degradation of aromatic hydrocarbons were detected for future study.
|State||Published - Dec 1 2019|
Bibliographical noteFunding Information:
This research was made possible by grants from The Gulf of Mexico Research Initiative to the C-IMAGE II, C-IMAGE III, and Deep-C consortia. This material is also based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. (2013172310). Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors(s) and do not necessarily reflect the views of the National Science Foundation. All data are publicly available through the Gulf of Mexico Research Initiative information & Data Cooperative (GRIIDC) at https:/data.gulfresearchinitiative.org (DOI: 10.7266/N7VD6X0R).
© 2019, The Author(s).
ASJC Scopus subject areas