Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China.
School of Environmental Science and Technology, Dalian University of Technology, Dalian, Liaoning 116024, China.
Sci Total Environ. 2023 Aug 15;886:163831. doi: 10.1016/j.scitotenv.2023.163831. Epub 2023 May 5.
A comprehensive understanding of ecological processes related to bacterial communities in these ecosystems is critical for improving the sustainability of estuarine-coastal ecosystem functions. However, the community composition, functional potential, and assembly mechanisms of bacterial community in metal(loid)-contaminated estuarine-coastal habitats remain poorly understood, especially along lotic systems extending from rivers to estuaries and to bays. Here, we collected sediment samples associated with sewage outlets from rivers (upstream/midstream of sewage outlet), estuaries (sewage outlets), and Jinzhou Bay (downstream of sewage outlets) within Liaoning Province, China in order to evaluate the relationships between microbiome and metal(loid) contamination. Sewage discharge markedly increased the concentrations of metal(loid)s in sediments, including of As, Fe, Co, Pb, Cd, and Zn. Significant discrepancies in alpha diversity and community composition were observed among the sampling sites. The above dynamics were primarily caused by salinity and metal(loid) concentrations (i.e., of As, Zn, Cd, and Pb). Furthermore, metal(loid) stress significantly increased abundances of metal(loid)-resistant genes, but decreased abundances of denitrification genes. Dechloromonas, Hydrogenophaga, Thiobacillus, and Leptothrix were denitrifying bacteria present within sediments of this estuarine-coastal ecosystem. Moreover, the stochastic processes dominated the community assembly in estuary offshore sites, while deterministic processes dominated river community assembly mechanisms. Salinity and total nitrogen concentration, rather than metal(loid) concentrations, governed the assembly processes in these sites. Overall, these elucidate mechanisms involved in constructing community diversities, functional potential, and assembly.
全面了解这些生态系统中与细菌群落相关的生态过程对于提高河口-沿海生态系统功能的可持续性至关重要。然而，金属（类）污染的河口-沿海生境中细菌群落的组成、功能潜力和组装机制仍知之甚少，特别是在从河流延伸到河口和海湾的流水系统中。在这里，我们收集了来自中国辽宁省河流（河流出水口的上游/中游）、河口（出水口）和锦州湾（出水口下游）与污水出口相关的沉积物样本，以评估微生物组与金属（类）污染之间的关系。污水排放显著增加了沉积物中金属（类）的浓度，包括砷、铁、钴、铅、镉和锌。采样点之间的 alpha 多样性和群落组成存在显著差异。上述动态主要是由盐度和金属（类）浓度（即砷、锌、镉和铅）引起的。此外，金属（类）胁迫显著增加了金属（类）抗性基因的丰度，但降低了反硝化基因的丰度。脱氯单胞菌、噬氢菌、硫杆菌和鞘铁菌是该河口-沿海生态系统沉积物中存在的反硝化细菌。此外，随机过程主导了河口近海站点的群落组装，而确定性过程主导了河流群落组装机制。盐度和总氮浓度而不是金属（类）浓度控制着这些位点的组装过程。总的来说，这些研究阐明了构建群落多样性、功能潜力和组装的机制。
