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Identification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing
|Title||Identification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||He, R, Wooller, MJ, Pohlman, JW, Catranis, C, Quensen, J, Tiedje, JM, Leigh, MBeth|
Arctic lakes are a significant source of the greenhousegas methane (CH4), but the role that methaneoxidizing bacteria (methanotrophs) play in limitingthe overall CH4 flux is poorly understood. Here, weused stable isotope probing (SIP) techniques to identifythe metabolically active aerobic methanotrophsin upper sediments (0–1 cm) from an arctic lake innorthern Alaska sampled during ice-free summerconditions. The highest CH4 oxidation potential wasobserved in the upper sediment (0–1 cm depth)with 1.59 mmol g wet weight-1 day-1 compared with thedeeper sediment samples (1–3 cm, 3–5 cm and5–10 cm), which exhibited CH4 oxidation potentialsbelow 0.4 mmol g wet weight-1 day-1. Both type I andtype II methanotrophs were directly detected in theupper sediment total communities using targetedprimer sets based on 16S rRNA genes. Sequencing of16S rRNA genes and functional genes (pmoA andmxaF) in the 13C-DNA from the upper sedimentindicated that type I methanotrophs, mainly Methylobacter,Methylosoma, Methylomonas and Methylovulummiyakonense, dominated the assimilation of CH4.Methylotrophs, including the genera Methylophilusand/or Methylotenera, were also abundant in the 13CDNA.Our results show that a diverse microbial consortiumacquired carbon from CH4 in the sediments ofthis arctic lake.