Microbial mercury methylation in Antarctic sea ice.
Atmospheric deposition of mercury onto sea ice and circumpolar sea water provides mercury for microbial methylation, and contributes to the bioaccumulation of the potent neurotoxin methylmercury in the marine food web. Little is known about the abiotic and biotic controls on microbial mercury methylation in polar marine systems. However, mercury methylation is known to occur alongside photochemical and microbial mercury reduction and subsequent volatilization. Here, we combine mercury speciation measurements of total and methylated mercury with metagenomic analysis of whole-community microbial DNA from Antarctic snow, brine, sea ice and sea water to elucidate potential microbially mediated mercury methylation and volatilization pathways in polar marine environments. Our results identify the marine microaerophilic bacterium Nitrospina as a potential mercury methylator within sea ice. Anaerobic bacteria known to methylate mercury were notably absent from sea-ice metagenomes. We propose that Antarctic sea ice can harbour a microbial source of methylmercury in the Southern Ocean.
School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia.
Caitlin M
CM
Gionfriddo
Wisconsin Water Science Center, US Geological Survey, Middleton, Wisconsin 53562, USA.
Michael T
MT
Tate
Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.|Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
Ryan R
0000-0001-8349-0778
RR
Wick
Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.|Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
Mark B
0000-0002-7689-6531
MB
Schultz
Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 USA.
Adam
A
Zemla
Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Michael P
MP
Thelen
School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia.
Robyn
R
Schofield
Wisconsin Water Science Center, US Geological Survey, Middleton, Wisconsin 53562, USA.
David P
DP
Krabbenhoft
Centre for Systems Genomics, University of Melbourne, Victoria 3010, Australia.|Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
Kathryn E
0000-0003-3949-2471
KE
Holt
School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia.
John W
JW
Moreau
D000864:Antarctic Regions; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D046448:Ice Cover / Q000737:chemistry / Q000382:microbiology*; D008628:Mercury / Q000378:metabolism*; D056186:Metagenomics; D008745:Methylation; D008767:Methylmercury Compounds / Q000032:analysis*; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology*; D012623:Seawater / Q000382:microbiology*; D012914:Snow / Q000382:microbiology
D008767:Methylmercury Compounds; D008628:Mercury
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