Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada)

• Published in: FEMS Microbiology Ecology
• Main Authors: Garneau, Marie-Ève, Michel, Christine, Meisterhans, Guillaume, Fortin, Nathalie, King, Thomas L., Greer, Charles W., Lee, Kenneth
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press 2016
• Subjects: arctic; sea ice; hydrocarbon biodegradation; bioremediation; 16S ribosomal RNA gene sequencing; microbial community fingerprinting; Northwest passage; Nunavut; Sea ice
• Online Access: https://doi.org/10.1093/femsec/fiw130; https://nrc-publications.canada.ca/eng/view/accepted/?id=7c0aa52f-edde-4536-bc0b-f3df34a692ee; https://nrc-publications.canada.ca/eng/view/object/?id=7c0aa52f-edde-4536-bc0b-f3df34a692ee; https://nrc-publications.canada.ca/fra/voir/objet/?id=7c0aa52f-edde-4536-bc0b-f3df34a692ee

The increasing accessibility to navigation and offshore oil exploration brings risks of hydrocarbon releases in Arctic waters. Bioremediation of hydrocarbons is a promising mitigation strategy but challenges remain, particularly due to low microbial metabolic rates in cold, ice-covered seas. Hydrocarbon degradation potential of ice-associated microbes collected from the Northwest Passage was investigated. Microcosm incubations were run for 15 days at -1.7°C with and without oil to determine the effects of hydrocarbon exposure on microbial abundance, diversity and activity, and to estimate component-specific hydrocarbon loss. Diversity was assessed with automated ribosomal intergenic spacer analysis and ion torrent 16S rRNA gene sequencing. Bacterial activity was measured by ³H-leucine uptake rates. After incubation, sub-ice and sea-ice communities degraded 94% and 48% of the initial hydrocarbons, respectively. Hydrocarbon exposure changed the composition of sea-ice and sub-ice communities; in sea-ice microcosms, Bacteroidetes (mainly Polaribacter) dominated whereas in sub-ice microcosms, Epsilonproteobacteria contribution increased, but that of Alphaproteobacteria and Bacteroidetes decreased. Sequencing data revealed a decline in diversity and increases in Colwellia and Moritella in oil-treated microcosms. Low concentration of dissolved organic matter (DOM) in sub-ice seawater may explain higher hydrocarbon degradation when compared to sea ice, where DOM was abundant and composed of labile exopolysaccharides. Peer reviewed: Yes NRC publication: Yes