Abstract Understanding the conditions of dissolved organic matter (DOM) release from thawing peat in the Arctic regions and identifying the pathways of processing DOM by soil and aquatic heterotrophic bacteria are critical in the context of rapid climate change. Until now, experimental approaches did not allow quantitative predictions of temperature and biota effects on carbon release from peat in permafrost-affected aquatic environments. In this study, we incubated frozen peat and its aqueous leachate at various temperatures (4, 25 or 45 °C), with and without culturable heterotrophic bacteria Iodobacter sp., extracted from thermokarst lakes, to quantify the release and the removal rate of organic carbon (OC) with time. The metabolic diversity of the native microbial community associated with the substrates involved in OC processing was also characterized. Transmission electron microscopy revealed that, after degradation, the associated bacteria are mostly located in the inner parts of plant cells, and that the degradation of organic matter around bacteria is more pronounced at 4 and 25 °C compared to 45 °C. The metabolic diversity of heterotrophic bacteria was equally high at 4 and 25 °C, but lower at 45 °C. Regardless of the microbial consortium (native community alone or with added culturable heterotrophs), both the OC release from peat and the OC removal from peat leachate by bacteria were similar at 4 and 25 °C. Very low apparent activation energies of DOM biodegradation between 4 and 25 °C (−4.23 ± 12.3 kJ mol−1) suggest that the short-period of surface water warming in summer would have an insignificant effect on DOM microbial processing. Such duration (1–3 weeks) is comparable with the water residence time in peat depressions and permafrost subsidences, where peat degradation and DOM microbial processing occur. This questions the current paradigm of a drastic effect of temperature rise on organic carbon release from frozen peatlands, and should be considered for modelling short-term climate impacts in these regions.

中文翻译：

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冷冻泥炭溶解有机物的有氧释放和生物降解：温度和异养细菌的影响

摘要 在气候快速变化的背景下，了解北极地区解冻泥炭释放溶解有机质 (DOM) 的条件并确定土壤和水生异养细菌处理 DOM 的途径至关重要。到目前为止，实验方法还不能定量预测温度和生物群对受永久冻土影响的水生环境中泥炭碳释放的影响。在这项研究中，我们在不同温度（4、25 或 45 °C）下孵育冷冻泥炭及其含水浸出液，有或没有可培养的异养细菌碘杆菌，从热岩溶湖泊中提取，以量化有机物的释放和去除率。碳 (OC) 随时间变化。还表征了与 OC 加工中涉及的底物相关的天然微生物群落的代谢多样性。透射电镜显示，降解后相关细菌大多位于植物细胞内部，与45°C相比，4和25°C时细菌周围有机物的降解更为明显。异养细菌的代谢多样性在 4 和 25°C 时同样高，但在 45°C 时较低。无论微生物群落（单独的本地群落还是添加了可培养的异养菌），在 4 和 25 °C 时，泥炭释放的 OC 和细菌从泥炭渗滤液中去除的 OC 都相似。在 4 到 25 °C (-4.23 ± 12. 3 kJ mol−1) 表明夏季短期地表水变暖对 DOM 微生物加工的影响不显着。这种持续时间（1-3 周）与泥炭洼地和永久冻土沉降中的水停留时间相当，泥炭降解和 DOM 微生物加工发生在这些地方。这对当前温度升高对冻结泥炭地的有机碳释放产生剧烈影响的范式提出了质疑，应考虑用于模拟这些地区的短期气候影响。