Microbial Community Structure in Ancient European Arctic Peatlands

Northern peatlands, which are crucial reservoirs of carbon and nitrogen (415 ± 150 and 10 ± 7 Pg, respectively), are vulnerable to microbial mineralization after permafrost thaw. This study was carried out in four key sites containing northern permafrost peatland, which are located along the southern cryolithozone. The aim of this study is to characterize amino acids and the microbial community composition in peat strata along a climate gradient. Amino acids and microbiota diversity were studied by liquid chromatography and a quantitative polymerase chain reaction. The share of amino acid fragments was 2.6–7.8, and it is highly significantly correlated (r = 0.87, −0.74 and 0.67, p ˂ 0.05) with the organic nitrogen concentration in the soil, the C/N ratio, and δ(15)N. The data shows the existence of a large pool of microorganisms concentrated in permafrost peatlands, and a vertical continuum of bacteria, archaea, and microscopic fungi along the peat profile, due to the presence of microorganisms in each layer, throughout all the peat strata. There is no significant correlation between microorganism distribution and the plant macrofossil composition of the peat strata. Determining factors for the development of microorganism abundance are aeration and hydrothermal conditions. The availability of nitrogen will limit the ability of plants and microorganisms to respond to changing environmental conditions; however, with the increased decomposition of organic matter, amino acids will be released as organic sources of nitrogen stored in the protein material of peat-forming plants and microbial communities, which can also affect the organic nitrogen cycle.