Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
J Environ Sci (China). 2021 Sep;107:205-217. doi: 10.1016/j.jes.2021.02.011. Epub 2021 Feb 26.
Interactions between dissolved organic matter (DOM) and bacteria are central in the biogeochemical cycles of aquatic ecosystems; however, the relative importance of biodegradable dissolved organic carbon (BDOC) compared with other environmental variables in structuring the bacterial communities needs further investigation. Here, we investigated bacterial communities, chromophoric DOM (CDOM) characteristics and physico-chemical parameters as well as examined BDOC via bioassay incubations in large eutrophic Lake Taihu, China, to explore the importance of BDOC for shaping bacterial community structures and co-occurrence patterns. We found that the proportion of BDOC (%BDOC) correlated significantly and positively with the DOC concentration and the index of the contribution of recent produced autochthonous CDOM (BIX). %BDOC, further correlated positively with the relative abundance of the tryptophan-like component and negatively with CDOM aromaticity, indicating that autochthonous production of protein-like CDOM was an important source of BDOC. The richness of the bacterial communities correlated negatively with %BDOC, indicating an enhanced number of species in the refractory DOC environments. %BDOC was identified as a significant stronger factor than DOC in shaping bacterial community composition and the co-occurrence network, suggesting that substrate biodegradability is more significant than DOC quantity determining the bacterial communities in a eutrophic lake. Environmental factors explained a larger proportion of the variation in the conditionally rare and abundant subcommunity than for the abundant and the rare bacterial subcommunities. Our findings emphasize the importance of considering bacteria with different abundance patterns and DOC biodegradability when studying the interactions between DOM and bacteria in eutrophic lakes.
溶解性有机质（DOM）与细菌之间的相互作用是水生生态系统生物地球化学循环的核心；然而，与其他环境变量相比，可生物降解溶解性有机碳（BDOC）在构建细菌群落结构方面的相对重要性仍需进一步研究。在这里，我们通过生物测定培养，在中国富营养化的太湖中调查了细菌群落、发色 DOM（CDOM）特征和理化参数，并检查了 BDOC，以探讨 BDOC 对塑造细菌群落结构和共存模式的重要性。我们发现，BDOC 的比例（%BDOC）与 DOC 浓度和近期产生的自生 CDOM 的贡献指数（BIX）呈显著正相关。%BDOC 进一步与色氨酸样成分的相对丰度呈正相关，与 CDOM 的芳香度呈负相关，表明自生蛋白样 CDOM 的产生是 BDOC 的重要来源。细菌群落的丰富度与%BDOC 呈负相关，表明在难降解 DOC 环境中物种数量增加。%BDOC 被确定为比 DOC 更重要的塑造细菌群落组成和共生网络的因素，这表明在富营养湖中，底物生物降解性比 DOC 数量更能决定细菌群落。与丰富和稀有细菌亚群相比，条件稀有和丰富亚群的变化更多地由环境因素来解释。我们的研究结果强调了在研究富营养湖中 DOM 与细菌相互作用时，考虑具有不同丰度模式和 DOC 生物降解性的细菌的重要性。
