Freshwater ecosystems are responsible for an important part of the methane (CH₄) emissions which are likely to change with global warming. This study aims to evaluate temperature-induced (from 5 to 20 °C) changes on microbial community structure and methanogenic pathways in five sub-Antarctic lake sediments from Magallanes strait to Cape Horn, Chile. We combined in situ CH₄ flux measurements, CH₄ production rates (MPRs), gene abundance quantification and microbial community structure analysis (metabarcoding of the 16S rRNA gene). Under unamended conditions, a temperature increase of 5 °C doubled MPR while microbial community structure was not affected. Stimulation of methanogenesis by methanogenic precursors as acetate and H₂/CO₂, resulted in an increase of MPRs up to 127-fold and 19-fold, respectively, as well as an enrichment of mcrA-carriers strikingly stronger under acetate amendment. At low temperatures, H₂/CO₂-derived MPRs were considerably lower (down to 160-fold lower) than the acetate-derived MPRs, but the contribution of hydrogenotrophic methanogenesis increased with temperature. Temperature dependence of MPRs was significantly higher in incubations spiked with H₂/CO₂ (c. 1.9 eV) compared to incubations spiked with acetate or unamended (c. 0.8 eV). Temperature was not found to shape the total microbial community structure, that rather exhibited a site-specific variability among the studied lakes. However, the methanogenic archaeal community structure was driven by amended methanogenic precursors with a dominance of Methanobacterium in H₂/CO₂-based incubations and Methanosarcina in acetate-based incubations. We also suggested the importance of acetogenic H₂-production outcompeting hydrogenotrohic methanogenesis especially at low temperatures, further supported by homoacetogen proportion in the microcosm communities. The combination of in situ-, and laboratory-based measurements and molecular approaches indicates that the hydrogenotrophic pathway may become more important with increasing temperatures than the acetoclastic pathway. In a continuously warming environment driven by climate change, such issues are crucial and may receive more attention.

淡水生态系统是甲烷（CH ₄）排放的重要部分，甲烷排放可能随着全球变暖而改变。这项研究的目的是评估温度引起的（从5到20°C）微生物群落结构和甲烷生成途径的变化，该过程从Magallanes海峡到智利合恩角的5个南极亚湖沉积物中。我们结合了原位CH ₄流量测量，CH ₄产生率（MPR），基因丰度定量和微生物群落结构分析（16S rRNA基因的超条形码）。在未修改的条件下，温度升高5°C使MPR倍增，而微生物群落结构未受影响。产甲烷的前驱物（如乙酸盐和H）刺激产甲烷作用₂ / CO ₂，导致增加的MPR的多达127倍和19倍，分别，以及的富集MCRA -carriers下乙酸修正案惊人地更强。在低温下，H ₂ / CO ₂衍生的MPR比乙酸盐衍生的MPR显着降低（低160倍），但氢营养型甲烷生成的贡献随温度增加而增加。在加有H ₂ / CO _2的培养物中，MPR的温度依赖性显着更高（c。1.9 eV）与掺有乙酸盐或未修正的培养物（c。0.8 eV）相比。未发现温度会影响整个微生物群落结构，而在所研究的湖泊之间却表现出特定地点的变异性。然而，产甲烷古细菌群落结构通过修正甲烷前体与的显性从动甲烷H中₂ / CO ₂的基于温育和甲烷在醋酸酯基的孵育。我们还提出了产乙酸的H _2产生胜过氢甲烷化甲烷生成的重要性，特别是在低温下，其在微观世界中由同质的乙酸根比例进一步支持。原位组合以及基于实验室的测量和分子方法表明，随着温度的升高，氢营养路径可能比乙酰碎裂路径更重要。在由气候变化驱动的持续变暖的环境中，此类问题至关重要，可能会引起更多关注。