Key Laboratory of Hydrometeorological Disaster Mechanism and Warning, Ministry of Water Resources, School of Hydrology and Water Resources, Nanjing University of Information Science and Technology, Nanjing 210044, China; State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Key Laboratory of Hydrometeorological Disaster Mechanism and Warning, Ministry of Water Resources, School of Hydrology and Water Resources, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Sci Total Environ. 2024 Nov 10;950:175273. doi: 10.1016/j.scitotenv.2024.175273. Epub 2024 Aug 5.
Northern peatlands are important carbon pools; however, differences in the structure and function of microbiomes inhabiting contrasting geochemical zones within these peatlands have rarely been emphasized. Using 16S rRNA gene sequencing, metagenomic profiling, and detailed geochemical analyses, we investigated the taxonomic composition and genetic potential across various geochemical zones of a typical northern peatland profile in the Changbai Mountains region (Northeastern China). Specifically, we focused on elucidating the turnover of organic carbon, sulfur (S), nitrogen (N), and methane (CH). Three geochemical zones were identified and characterized according to porewater and solid-phase analyses: the redox interface (<10 cm), shallow peat (10-100 cm), and deep peat (>100 cm). The redox interface and upper shallow peat demonstrated a high availability of labile carbon, which decreased toward deeper peat. In deep peat, anaerobic respiration and methanogenesis were likely constrained by thermodynamics, rather than solely driven by available carbon, as the acetate concentrations reached 90 μmol·L. Both the microbial community composition and metabolic potentials were significantly different (p < 0.05) among the redox interface, shallow peat, and deep peat. The redox interface demonstrated a close interaction between N, S, and CH cycling, mainly driven by Thermodesulfovibrionia, Bradyrhizobium, and Syntrophorhabdia metagenome-assembled genomes (MAGs). The archaeal Bathyarchaeia were indicated to play a significant role in the organic carbon, N, and S cycling in shallow peat. Although constrained by anaerobic respiration and methanogenesis, deep peat exhibited a higher metabolic potential for organic carbon degradation, primarily mediated by Acidobacteriota. In terms of CH turnover, subsurface peat (10-20 cm) was a CH production hotspot, with a net turnover rate of ∼2.9 nmol·cm·d, while the acetoclastic, hydrogenotrophic, and methylotrophic methanogenic pathways all potentially contributed to CH production. The results of this study improve our understanding of biogeochemical cycles and CH turnover along peatland profiles.
北方泥炭地是重要的碳库；然而，很少强调栖息在这些泥炭地中不同地球化学带的微生物群落的结构和功能差异。本研究使用 16S rRNA 基因测序、宏基因组分析和详细的地球化学分析，调查了长白山地区（中国东北）典型北方泥炭地剖面不同地球化学带的分类组成和遗传潜力。具体而言，我们专注于阐明有机碳、硫 (S)、氮 (N) 和甲烷 (CH) 的转化。根据孔隙水和固相分析，确定并描述了三个地球化学带：氧化还原界面（<10 cm）、浅层泥炭（10-100 cm）和深层泥炭（>100 cm）。氧化还原界面和上部浅层泥炭表现出较高的易降解碳的可用性，而深层泥炭中的碳可用性降低。在深层泥炭中，由于乙酸浓度达到 90 μmol·L，可能受热力学限制而非仅受可用碳驱动，导致厌氧呼吸和产甲烷作用受到限制。微生物群落组成和代谢潜力在氧化还原界面、浅层泥炭和深层泥炭之间存在显著差异（p < 0.05）。氧化还原界面表现出 N、S 和 CH 循环之间的密切相互作用，主要由 Thermodesulfovibrionia、Bradyrhizobium 和 Syntrophorhabdia 宏基因组组装基因组（MAGs）驱动。古菌 Bathyarchaeia 被表明在浅层泥炭中对有机碳、N 和 S 循环具有重要作用。尽管受厌氧呼吸和产甲烷作用限制，但深层泥炭表现出更高的有机碳降解代谢潜力，主要由 Acidobacteriota 介导。就 CH 转化而言，次表层泥炭（10-20 cm）是 CH 产生的热点，净转化速率约为 2.9 nmol·cm·d，而乙酰营养型、氢营养型和甲基营养型产甲烷途径都可能有助于 CH 产生。本研究的结果提高了我们对沿泥炭地剖面的生物地球化学循环和 CH 转化的理解。
