Methanogenesis and methanogenic pathways in a peat from subarctic permafrost

Summary Few studies have dealt so far with methanogenic pathways and populations in subarctic and arctic soils. We studied the effects of temperature on rates and pathways of CH 4 production and on the relative abundance and structure of the archaeal community in a mildly acidic peat from a permafrost region in Siberia (67°N). We monitored the production of CH 4 and CO 2 over time and measured the consumption of Fe(II), ethanol and volatile fatty acids. All experiments were performed with and without specific inhibitors [2‐bromoethanesulfonate (BES) for methanogenesis and CH 3 F for acetoclastic methanogenesis]. The optimum temperature for methanogenesis was between 26°C and 28°C [4.3 μmol CH 4  (g dry weight) −1  day −1 ], but the activity was high even at 4°C [0.75 μmol CH 4  (g dry weight) −1