Varun Gupta (Department of Geography)
Abstract for Oral Presentation for 2011 CSM Conference:
Active methanotrophs in two contrasting North American peatland ecosystems revealed using DNA stable-isotope probing (SIP).
The active methanotroph community was investigated in two contrasting North American peatlands, a nutrient rich sedge fen and nutrient poor Sphagnum bog using in vitro incubations and 13C-DNA stable-isotope probing (SIP) to measure methane (CH4) oxidation rates and label active microbes followed by fingerprinting and sequencing of bacterial and archaeal 16S rDNA and methane monooxygense (pmoA and mmoX) genes. Rates of CH4 oxidation were slightly, but significantly, faster in the bog and methanotrophs belonged to the class Alphaproteobacteria and were similar to other methanotrophs of the genera Methylocystis, Methylosinus, and Methylocapsa or Methylocella detected in, or isolated from, European bogs. The fen had a greater phylogenetic diversity of organisms that had assimilated 13C, including methanotrophs from both the Alpha and Gammaproteobacteria classes and other potentially non-methanotrophic organisms that were similar to bacteria detected in a UK and Finnish fen. Based on similarities between bacteria in our sites and those in Europe, including Russia, we concude that site physicochemical characteristics rather than biogeography controlled the phylogenetic diversity of active methanotrophs and that differences in phylogenetic diversity between the bog and fen did not relate to measured CH4 oxidation rates. A single crenarchaeon in the bog site appeared to be assimilating 13C labelling in 16S rDNA, however its phylogenetic similarity to other CO2-utilizing archaea probably indicates that this organism is not directly involved in CH4 oxidation in peat.
Information about wetlands/peatlands:
Wetlands are the largest global natural source of atmospheric methane with an estimate emission of 100-200Tg/year. There are five distinct wetlands classes in Canada as recognized by The Canadian Wetland Classification System: namely, bog, fen, marsh, swamp, and shallow open water. The Northern peatlands mainly consists of bogs and fens and are found notably in Canada, Russia, Finland, Poland, Germany, and Scotland covering about 3% of global land mass (Thormann, 2005). Peatlands covers about 14% of the Canadian landscape, thus making it very essential for us to understand this fragile ecosystem. Methane is 20 to 30 times more efficient greenhouse gas than carbon dioxide, hence even a small amount does a great deal of warming.