Spatiotemporal variations in the abundances of the prokaryotic rRNA genes, <Emphasis Type="Italic">pmoA</Emphasis>, and <Emphasis Type="Italic">mcrA</Emphasis> in the deep layers of a peat bog in Sarobetsu-genya wetland,Japan

Spatiotemporal variations in microbial gene abundances were investigated to identify potential zones of methanotroph and methanogen biomass in a peat bog in Sarobetsu-genya wetland. The abundances of the bacterial and archaeal 16S rRNA genes, pmoA, and mcrA were 10⁷–10⁹, 10⁷–10⁸, 10⁴–10⁶, and 10⁴–10⁷ copies g⁻¹ dry peat, respectively. Correlation analysis based on microbial gene abundances and environmental factors showed that the spatiotemporal distributions of the abundances of the four microbial genes in peat layers were similar. The mcrA abundance showed a significant negative correlation with the dissolved organic carbon content and a significant positive correlation with the peat temperature. The pmoA abundance was not detectable during the spring thaw when the lowest peat temperature at a depth of 50 cm was recorded. At a depth of 200 cm, the peat temperature exceeded 6°C throughout the year, and the mcrA abundance exceeded 10⁴ copies g⁻¹ dry peat. These results indicate that the seasonal microbial activity related to methane should be evaluated in not only the shallow but also the deep peat layers in order to elucidate the methane dynamics in boreal wetlands.