Investigating the critical role of carbon cycling feedback to warming is essential for understanding future biosphere development. One of the current challenges is that the warming effect on carbon cycling is inconsistent across various aquatic ecosystems. It was postulated that the composition of dissolved organic matter (DOM) and the microbial community influenced the response of carbon metabolism to warming. To test our hypothesis, we conducted a microcosm study in which three key factors were manipulated: initial DOM composition (adjusting the ratio of autochthonous and allochthonous substrates), bacterioplankton community history (characterized by two distinct sources of bacterioplankton community), and temperature (ambient and 4 °C warming). The results demonstrated that the initial composition of DOM exerted a dominant influence on carbon metabolism. In contrast, the history of bacterioplankton community influenced the active taxa and functional traits. The log-response ratio approach revealed that the warming treatment affected bacterial carbon demand (BCD) and bacterial growth efficiency (BGE). A piecewise structural equation model further validated the paths by which warming altered BCD, particularly by changing the consumption of fluorescent DOM, and altered BGE, by affecting the active bacterioplankton. Our study demonstrated that the impact of warming on carbon cycling was context-dependent, with particular relevance to the history and dynamics of bacterioplankton community in this process. Given ongoing changes in lacustrine environments, a more comprehensive understanding of the interactions between DOM and microbes is essential for the accurate prediction of future carbon cycling.

中文翻译：

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变暖对中上层碳代谢的影响与底物组成和浮游细菌群落历史有关


研究碳循环反馈对变暖的关键作用对于理解未来的生物圈发展至关重要。当前的挑战之一是，变暖对碳循环的影响在各种水生生态系统中并不一致。据推测，溶解有机物 （DOM） 的组成和微生物群落影响了碳代谢对变暖的响应。为了检验我们的假设，我们进行了一项微观世界研究，其中操纵了三个关键因素：初始 DOM 组成（调整原生底物和异质底物的比例）、浮游细菌群落历史（以浮游细菌群落的两个不同来源为特征）和温度（环境和 4 °C 变暖）。结果表明，DOM 的初始组成对碳代谢产生了主导影响。相比之下，浮游细菌群落的历史影响了活跃的分类群和功能性状。对数响应比方法显示，增温处理影响细菌碳需求 （BCD） 和细菌生长效率 （BGE）。分段结构方程模型进一步验证了变暖改变 BCD 的路径，特别是通过改变荧光 DOM 的消耗，以及通过影响活跃的浮游细菌来改变 BGE。我们的研究表明，变暖对碳循环的影响是依赖于环境的，与这一过程中浮游细菌群落的历史和动态特别相关。鉴于湖泊环境的持续变化，更全面地了解 DOM 和微生物之间的相互作用对于准确预测未来的碳循环至关重要。