Microbial N2 fixation (diazotrophy) represents an important nitrogen source to oligotrophic
peatland ecosystems, which are important sinks for atmospheric CO2 and are susceptible to
the changing climate. The objectives of this study were (i) to determine the active microbial
group and type of nitrogenase mediating diazotrophy in an ombrotrophic Sphagnum-
dominated peat bog (the S1 peat bog, Marcell Experimental Forest, Minnesota, USA); and
(ii) to determine the effect of environmental parameters (light, O2, CO2, and CH4) on …

… enzymatic pathways of peatland diazotrophy, as well as the metabolically active
microbial 42 … possible that diverse diazotrophs exist within defined niches of peatland
environments (60). 63 Diazotrophy is catalyzed by the nitrogenase metalloenzyme, a
complex of thee subunits 64 …