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. 2014 Nov;8(11):2305-16.
doi: 10.1038/ismej.2014.59. Epub 2014 Apr 17.

Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet

Markus Dieser  1 , Erik L J E Broemsen  1 , Karen A Cameron  2 , Gary M King  1 , Amanda Achberger  1 , Kyla Choquette  3 , Birgit Hagedorn  3 , Ron Sletten  4 , Karen Junge  2 , Brent C Christner  1
Affiliations

Molecular and biogeochemical evidence for methane cycling beneath the western margin of the Greenland Ice Sheet

Markus Dieser et al. ISME J. 2014 Nov.

Abstract

Microbial processes that mineralize organic carbon and enhance solute production at the bed of polar ice sheets could be of a magnitude sufficient to affect global elemental cycles. To investigate the biogeochemistry of a polar subglacial microbial ecosystem, we analyzed water discharged during the summer of 2012 and 2013 from Russell Glacier, a land-terminating outlet glacier at the western margin of the Greenland Ice Sheet. The molecular data implied that the most abundant and active component of the subglacial microbial community at these marginal locations were bacteria within the order Methylococcales (59-100% of reverse transcribed (RT)-rRNA sequences). mRNA transcripts of the particulate methane monooxygenase (pmoA) from these taxa were also detected, confirming that methanotrophic bacteria were functional members of this subglacial ecosystem. Dissolved methane ranged between 2.7 and 83 μM in the subglacial waters analyzed, and the concentration was inversely correlated with dissolved oxygen while positively correlated with electrical conductivity. Subglacial microbial methane production was supported by δ(13)C-CH4 values between -64‰ and -62‰ together with the recovery of RT-rRNA sequences that classified within the Methanosarcinales and Methanomicrobiales. Under aerobic conditions, >98% of the methane in the subglacial water was consumed over ∼30 days incubation at ∼4 °C and rates of methane oxidation were estimated at 0.32 μM per day. Our results support the occurrence of active methane cycling beneath this region of the Greenland Ice Sheet, where microbial communities poised in oxygenated subglacial drainage channels could serve as significant methane sinks.

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Figures

Figure 1
Figure 1
Sampling locations on the western margin of the Greenland Ice Sheet. The sites were located east of Kangerlussuaq. (A) Subglacial outflow (SUB-RG) and supraglacial stream (SUPRA-RG) at Russell Glacier. (A1) Early season, (A2) mid-season and (A3) late season discharge at SUB-RG. (B) Moraine stream (MS).
Figure 2
Figure 2
(a) Dissolved methane concentrations in glacial discharge (●) and after 4–5 months of incubation at 4 °C ([Image: see text]). (b) Correlations between dissolved methane, electrical conductivity (▪) and dissolved oxygen ([Image: see text]) in subglacial discharge at Russell Glacier (SUB-RG) and the moraine stream (MS). Note that different scales are used on the x axes.
Figure 3
Figure 3
Aerobic oxidation of methane in subglacial samples that were incubated for 33 days at ∼4 °C. Error bars denote the standard deviation from the mean of triplicate measurements.
Figure 4
Figure 4
Seasonal distribution of the microbial assemblage unique to the subglacial outflow at Russell Glacier (SUB-RG). The relative abundance of (a) 16S rRNA gene and (b) 16S RT-rRNA sequences. The missing sample on 25 June in the 16S rRNA gene data set was the result of a technical error during sequencing.
Figure 5
Figure 5
Phylogenetic analysis of (a) 16S RT-rRNA sequences related to type I and type II methanotrophs and (b) PmoA amino-acid sequences from subglacial samples at Russell Glacier (SUB-RG). Filled circles (●) and bold lettering indicate sequences obtained in this study. The 16S RT-rRNA and PmoA amino-acid neighbor joining trees were rooted with the 16S rRNA gene of Clostridium frigoriphilum and AmoA sequences of the family Nitrosomonadaceae, respectively. Evolutionary distance was computed using the Jukes-Cantor method. Gaps and missing data were eliminated from the alignments. Bootstrap values (1000 replications) >50% are shown. The scale bar represents 3% and 10% divergence of nucleic acid sequence and amino-acid sequence, respectively. The numbers in brackets following the OTU indicate the number of sequences represented for each OTU. Environmental clades of methanotrophs were included in the tree (upland soil clade (USC), glacial forefield soils, Greenland and Jasper Ridge clade (JR1)) for reference. Genbank accession numbers are shown in parentheses.
Figure 6
Figure 6
Phylogenetic analysis of methanogen 16S RT-rRNA clones from supraglacial (SUPRA-RG) and subglacial (SUB-RG) water samples at Russell Glacier using the neighbor joining method. Evolutionary distances were computed using the Jukes-Cantor method. Evolutionary analyses were conducted in MEGA v5.2.2. The tree is rooted with the 16S rRNA gene sequence of Clostridium frigoriphilum and bootstrap values (1000 replications) >50% are shown. The scale bar represents 5% divergence of nucleic acid sequence. The sequences obtained are shown in bold: (♦) SUPRA-RG OTUs, (●) SUB-RG OTUs; numbers in parentheses indicate the number of clones grouped with a ⩾97% identity level. Selected 16S rRNA sequences of clone sequences obtained from other subglacial systems and type species were obtained from public databases. Genbank accession numbers are shown in parentheses.
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References

    1. Aebly FA, Fritz SC. (2009). Palaeohydrology of Kangerlussuaq (Søndre Strømfjord), West Greenland during the last ∼8000 years. Holocene 19: 91–104.
    1. Amaral JA, Knowles R. (1994). Methane metabolism in a temperate swamp. Appl Environ Microbiol 60: 3945–3951. - PMC - PubMed
    1. Amaral JA, Archambault C, Richards SR, Knowles R. (1995). Denitrification associated with Groups I and II methanotrophs in a gradient enrichment system. FEMS Microbiol Ecol 18: 289–298.
    1. Bárcena TG, Yde JC, Finster KW. (2010). Methane flux and high-affinity methanotrophic diversity along the chronosequence of a receding glacier in Greenland. Ann Glaciol 51: 23–31.
    1. Bates ST, Berg-Lyons D, Caporaso JG, Walters WA, Knight R, Fierer N. (2011). Examining the global distribution of dominant archaeal populations in soil. ISME J 5: 08–917. - PMC - PubMed

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