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Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

TitleDiversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments
Publication TypeJournal Article
Year of Publication2012
AuthorsHe, R, Wooller, MJ, Pohlman, JW, Quensen, J, Tiedje, JM, Leigh, MBeth
JournalThe ISME Journal
VolumeEpub ahead of print

Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that entersthe atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood.We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichmentcultures to determine the identity and diversity of active aerobic methanotrophs in the watercolumns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope ofAlaska and a subarctic taiga lake (Lake Killarney) in Alaska’s interior. The water column CH4oxidation potential for these shallow (B2m deep) lakes was greatest in hypoxic bottom water fromthe subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures ofplanktonic methanotrophs from the water columns. In the sediments, type I methanotrophs(Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm)were most active in assimilating CH4, whereas the type I methanotroph Methylobacterand/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in thedeeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance ofmethylotrophs also actively utilized CH4-derived carbon. This study provides new insight into theidentity and activity of methanotrophs in the sediments and water from high-latitude lakes.The ISME Journal advance online publication, 17 May 2012; doi:10.1038/ismej.2012.34Subject Category: microbial ecology and functional diversity of natural habitatsKeywords: methanotrophs; CH4 oxidation potential; arctic lakes; stable isotope probing

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