Diesel and Crude Oil Biodegradation by Cold-Adapted Microbial Communities in the Labrador Sea

摘要

Oil spills in the subarctic marine environment off the coast of Labrador, Canada, are increasingly likely due to potential oil production and increases in ship traffic in the region. To understand the microbiome response and how nutrient biostimulation promotes biodegradation of oil spills in this cold marine setting, marine sediment microcosms amended with diesel or crude oil were incubated at in situ temperature (4°C) for several weeks. Sequencing of 16S rRNA genes following these spill simulations revealed decreased microbial diversity and enrichment of putative hydrocarbonoclastic bacteria that differed depending on the petroleum product. Metagenomic sequencing revealed that the genus Paraperlucidibaca harbors previously unrecognized capabilities for alkane biodegradation, which were also observed in Cycloclasticus. Genomic and amplicon sequencing together suggest that Oleispira and Thalassolituus degraded alkanes from diesel, while Zhongshania and the novel PGZG01 lineage contributed to crude oil alkane biodegradation. Greater losses in PAHs from crude oil than from diesel were consistent with Marinobacter, Pseudomonas_D, and Amphritea genomes exhibiting aromatic hydrocarbon biodegradation potential. Biostimulation with nitrogen and phosphorus (4.67 mM NH_4Cl and 1.47 mM KH_2PO_4) was effective at enhancing n-alkane and PAH degradation following low-concentration (0.1 vol/vol) diesel and crude oil amendments, while at higher concentrations (1 vol/vol) only n-alkanes in diesel were consumed, suggesting toxicity induced by compounds in unrefined crude oil. Biostimulation allowed for a more rapid shift in the microbial community in response to petroleum amendments, more than doubling the rates of CO_2 increase during the first few weeks of incubation. IMPORTANCE Increases in transportation of diesel and crude oil in the Labrador Sea will pose a significant threat to remote benthic and shoreline environments, where coastal communities and wildlife are partic