Distribution of PAHs and the PAH-degrading bacteria in the deep-sea sediments of the high-latitude Arctic Ocean

[摘要] Polycyclic aromatic hydrocarbons (PAHs) are common organic pollutants thatcan be transferred long distances and tend to accumulate in marine sediments.However, less is known regarding the distribution of PAHs and their naturalbioattenuation in the open sea, especially the Arctic Ocean. In this report,sediment samples were collected at four sites from the Chukchi Plateau to theMakarov Basin in the summer of 2010. PAH compositions and totalconcentrations were examined with GC-MS. The concentrations of 16EPA-priority PAHs varied from 2.0 to 41.6 ng g⁻¹ dry weight anddecreased with sediment depth and movement from the southern to the northernsites. Among the targeted PAHs, phenanthrene was relatively abundant in allsediments. The 16S rRNA gene of the total environmental DNA was analyzed withIllumina high-throughput sequencing (IHTS) to determine the diversity ofbacteria involved in PAH degradation in situ. The potential degradersincludingCycloclasticus,Pseudomonas, Halomonas, Pseudoalteromonas,Marinomonas, Bacillus, Dietzia,Colwellia,Acinetobacter, Alcanivorax,Salinisphaera andShewanella, withDietzia as the most abundant, occurred in all sediment samples.Meanwhile, enrichment with PAHs was initiated onboard and transferred to thelaboratory for further enrichment and to obtain the degrading consortia. Mostof the abovementioned bacteria in addition toHahella,Oleispira, Oceanobacter andHyphomonas occurred alternately as predominantmembers in the enrichment cultures from different sediments based on IHTS andPCR-DGGE analysis. To reconfirm their role in PAH degradation, 40 differentbacteria were isolated and characterized, among whichCycloclasticus Pseudomonas showed the best degradation capability under lowtemperatures. Taken together, PAHs and PAH-degrading bacteria were widespreadin the deep-sea sediments of the Arctic Ocean. We propose that bacteria of Cycloclasticus,Pseudomonas,Pseudoalteromonas, Halomonas, Marinomonas andDietzia may play themost important role in PAH mineralization in situ.

[学科分类] 地球化学与岩石