Effect of different ecological treatment methods on microbial community in black and odorous sediment of urban river

Abstract

底泥细菌代谢是城市河道底泥代谢物的主要来源，最终决定城市河道的生态状况.本文研究了黑臭河道底泥经添加硝酸钙、生物促生剂和种植沉水植物处理后底泥中细菌群落结构的响应，以期为城市黑臭河道细菌群落的改善和综合治理提供理论依据.实验结果表明：经过不同生态处理后，上覆水中，添加硝酸钙组总氮（TN）含量显著高于对照组，添加生物促生剂组溶解氧浓度显著高于对照组.沉积物中，所有处理组的氧化还原电位值（ORP）均显著高于对照组，种植沉水植物组和添加硝酸钙组TN含量均显著低于对照组，沉积物理化性质得到一定改善.对不同生态处理组底泥细菌群落的研究发现，处理组底泥细菌群落产生了较大变化，且不同处理组细菌群落变化不同，生物促生剂组底泥中细菌的Sobs指数和Chao 1指数显著高于对照组和硝酸钙组，且生物促生剂组Shannon指数和PD指数显著高于硝酸钙组.Proteobacteria（Deltaproteobacteria、Betaproteobacteria、Gammaproteobacteria）、Chloroflexi、Firmicutes、Bacteroidetes和Spirochaetae是各实验组的主要优势菌门；非度量多维尺度分析表明：硝酸钙和生物促生剂的投加可明显改变底泥细菌群落结构组成.在属水平上，uncultured_Anaerolineaceae、Ferribacterium、uncultured_Xanthomonadales_Incertae_Sedis是导致底泥细菌群落发生变化的主要菌属.冗余分析结果表明，底泥ORP的变化是驱动细菌群落结构变化的关键环境因素.;Sediment microorganisms are the main source of sediment metabolism in urban rivers, which ultimately determine the ecological status of the rivers. In this paper, to analyze the effect of different ecological treatments on sediment microbial community, we established artificial mesocosms to mimic sediment status of the black-stinking river with different ecological treatments as calcium nitrate, bio-energizer addition, and submerged macrophytes transplantation. Illumina Miseq sequencing was applied to reveal the bacteria community variations of all treated and untreated sediments. The results showed that in the overlying water, the total nitrogen (TN) content of calcium nitrate addition group was significantly higher than that in the control group, dissolved oxygen concentration in the bio-energizer addition group was significantly higher than that in the control group. In the sediment, the oxidation reduction potential (ORP) values of all the treatment groups were significantly higher than those in the control group; TN content of calcium nitrate addition group and submerged macrophytes transplantation group were both significantly lower than those in the control group, which indicate the improvement of sediment status of treatment group. Bacterial communities were also varied in treatment group, and showed diverse variations with different treatments. The Sobs and Chao 1 microbial diversity indices in the bio-energizer addition group were both significantly higher than those in the control group and calcium nitrate addition group; the Shannon and PD diversity indices for microbes in the bio-energizer addition sediment were both significantly higher than those in calcium nitrate addition group. All sediment microbial communities were dominated by Proteobacteria (Deltaproteobacteria, Betaproteobacteria, Gammaproteobacteria), Chloroflexi, Firmicutes, Bacteroidetes and Spirochaetae phyla. Nonmetric multidimensional scaling analysis showed that the addition of calcium nitrate and bio-energizer can significantly alter the composition of bacterial community structure. Uncultured_Anaerolineaceae, Ferribacterium and uncultured_Xanthomonadales_Incertaeae_Sedis were the main genus causing variations in the bacterial community. Redundancy analysis indicated that the change of sediment ORP is a key environmental factor driving the variation of bacterial community structure.