输水情景下白洋淀好氧反硝化菌群落对溶解性有机物的响应

溶解性有机物（DOM）是影响微生物群落演变的重要因素，而生态输水是白洋淀的一个重要特征，为了探究输水情境下DOM对好氧反硝化菌的影响，本文结合水体DOM的组分解析和好氧反硝化高通量测序技术，进行了水体好氧反硝化菌对DOM的响应研究.结果显示，白洋淀水体DOM的相对浓度存在显著差异，河口区要低于内部区；DOM呈现出较强自生源特征，河口区具有更高的分子量和更强的腐殖化；平行因子法解析出3种类蛋白组分和1种类腐殖质组分，类蛋白组分占比达到35.64%~96.38%，与荧光区域积分得到类蛋白占主体的结果相一致.与此同时，该时期水体好氧反硝化菌主要属于变形菌门（Protebacterice），主要包括Cupriavidus、Aeromonas、Thauera、Shewanella和Pseudomonas，与随机森林筛选出的指示物种相一致；网络分析得到35个网络关键节点，主要隶属于Thauera、Cupriavidus以及Unclassified_bacteria；冗余分析（RDA）显示类腐殖质物质是影响水体整体好氧反硝化菌群落组成的因子，类蛋白物质是影响指示物种群落和关键节点群落结构分布的重要因素.综上可知，水体溶解性有机物中类蛋白组分可以作为筛选适于生态输水期水体特征的耐低温高效好氧反硝化菌的碳源选择.

Structure of Aerobic Denitrification Bacterial Community in Response to Dissolved Organic Matter in Baiyangdian Lake During the Water Delivery Period

Dissolved organic matter (DOM) plays an important role in the evolution of microbial communities. Meanwhile, ecological water delivery is an important feature of Baiyangdian Lake. To explore how the structure of the aerobic denitrification bacteria community responds to DOM during the water delivery period, the DOM components of water were examined and high-throughput sequencing of aerobic denitrification bacteria was performed. The results showed significant differences in DOM concentration in Baiyangdian Lake, with the estuary area exhibiting lower DOM concentrations. The water exhibited strong autogenous source, while DOM in the estuary area had a higher molecular weight and degree of humification. Three protein-like substances (C1, C2, and C4) and one humic-like substance (C3) were identified through PARAFAC. The protein-like substances accounted for the major proportion of DOM, which was consistent with the results of fluorescence regional integration (FRI). The genera of the water body were mainly in the Protebacterice phylum, including Cupriavidus, Aeromonas, Thauera, Shewanella, and Pseudomonas. Meanwhile, Cupriavidus, Thauera, Shewanella, Agrobacterium, and Pseudomonas were the main indicator species, according to random forest (RF) analysis. Through network analysis, 35 key nodes of the network were obtained, belonging to Thauera, Cupriavidus, and Unclassified_bacteria, respectively. Redundancy analysis (RDA) showed that a humic-like substance was the main environmental factor regulating the whole structure of the aerobic denitrification bacterial community, while protein-like substances played important roles in changes to the indicator species and key nodes of the community. Overall, protein-like substances could provide an important reference for selecting carbon sources during the screening of efficient and cold resistance aerobic denitrification bacteria that are adapted to actual water bodies.