Biodegradation of weathered crude oil by microbial communities in solid and melted sea ice

Assessment of Hydrocarbon Degradation Potential in Microbial Communities in Arctic Sea Ice

“…The prokaryotic community of Ofotfjorden seawater used in this study appeared to be rich in the variety of microorganisms previously associated with petroleum hydrocarbon degradation, especially from the classes of Alpha-and Gammaproteobacteria. The proportion of genera known to contain HDOs was 2.2% higher in the SI community compared to SW, whereas in SIO, the proportion of HDOs was the highest and exceeded SI by 2.8% suggesting, contrary to some previous reports [28], a selective pressure of crude oil upon the sea ice prokaryotic community. The dominant part of HDO-containing genera was similar in both sea ice metagenomes, consisting of several cold-adapted genera (i.e., Colwellia, Pseudoalteromonas, Pseudomonas, Bermanella, Sulfitobacter, and Glaciecola) [20,62,63].…”

“…Actinomarina were prominent in SW, but their proportions decreased in both sea ice metagenomes, probably due to their sensitivity to lower temperatures [52,53]. The higher proportions of several Gammaproteobacterial sea ice-inhabiting genera, such as Bermanella, Colwellia and Glaciecola [48], which are also known to contain oil hydrocarbon-degrading organisms [27,54], in SIO compared to uncontaminated sea ice, suggests that crude oil encapsulated in ice affects the structure of the prokaryotic community, in contrast to some previous reports [28].…”

“…However, the increase in HDO proportion in the oil-contaminated ice prokaryotic community might not translate to significant hydrocarbon degradation activity [28,69], even in the presence of dispersants [27]. At low temperatures, below −5 • C, oil viscosity is high and sea ice is considered impermeable [28,70].…”

“…However, the increase in HDO proportion in the oil-contaminated ice prokaryotic community might not translate to significant hydrocarbon degradation activity [28,69], even in the presence of dispersants [27]. At low temperatures, below −5 • C, oil viscosity is high and sea ice is considered impermeable [28,70]. In these conditions, oil can stay in small brine channels where the biodegradation is restricted due to the small contact area between ice-inhabiting HDOs and substrate as well as high salinity [69]; however, in some cases, it can migrate through ice to underlying water [71].…”

“…The microbiome of Arctic sea ice has not yet been sufficiently studied, even though this knowledge would help to develop effective methods for spilled oil cleanup from below or inside of the sea ice [25,26]. Microorganisms from melted sea ice have been shown to degrade oil compounds in the Arctic region, whereas different microbial consortia from seawater have also been reported to take part in this process [5,27,28]. Bacterial genera such as Pelagibacter, Octadecabacter, Sulfitobacter, Colwellia [29], Cycloclasticus [29,30], Alcanivorax, Marinobacter, Thallassolituus [30], and Oleispira [29][30][31], to name a few, are often associated with oil compound degradation in Arctic areas.…”