Submerged macrophytes-biofilm symbionts are sensitive to water pollution and can be possibly used as the bio-indicators of aquatic ecosystems. However, the physiological responses of submersed macrophyte and microbial community to environmental pollution remain unclear. In this study, impacts of three kinds of treated or without treated sewage (JP, EP and CP) on Vallisnerian natans and microbial community were investigated. Compared with control, chlorophyll(a), carbohydrates and relative electrical conductivity (REC) in V. natans leaves and dissolved oxygen in overlaying water decreased in three treatments within 21 days. Microbial α-diversity values in three media were in sequence: surface sediments > epiphytic biofilm > overlying water. Cluster analyses showed that microbial community were more similar to each other within the same media regardless of nutrients. The species losses and replacements almost contributed equally to β-diversity among three media, suggesting these organisms can be potential microbial indicators. Several typical bacterioplankton Actinobacteria, Flavobacteriia, zooplankton Arthropoda and algae Cryptomonadales were dominant in water samples, while Firmicutes and Chloroflexi as well as protozoa Rhizaria and Amoebozoa had higher abundances in surface sediments than other two media. Genera conferring to biofilm formation or pollutant removal (Cellvibrio, Chitinophaga, Ohtaekwangia and Uliginosibacterium) were detected in epiphytic biofilm. Network analysis results showed that there were more complex interactions among microbes in epiphytic biofilm than overlying water and surface sediment. Our results highlighted that REC can be a good stress indicator of submersed macrophyte, while nutrients level and spatial variations caused differences in microbial community might be used as microbial indicators of water quality in submersed macrophyte-dominated water column. These data will provide useful information for the best management practice to protect aquatic ecosystems.

沉水植物-生物膜共生体对水体污染敏感，可作为水生生态系统的生物指标。然而，沉水植物和微生物群落对环境污染的生理反应仍不清楚。在这项研究中，研究了三种处理或未经处理的污水（JP、EP 和 CP）对Vallisnerian natans和微生物群落的影响。与对照相比，V. natans 中的叶绿素 (a)、碳水化合物和相对电导率 (REC)21 d 内，3 个处理的叶片和覆盖水中溶解氧均下降。三种介质中微生物α-多样性值依次为：表层沉积物>附生生物膜>上覆水。聚类分析表明，无论营养如何，同一培养基中的微生物群落彼此更相似。物种损失和替代对三种介质中 β 多样性的贡献几乎相同，这表明这些生物体可能是潜在的微生物指标。几种典型的浮游细菌放线菌、黄杆菌、浮游动物节肢动物和藻类隐藻在水样中占优势，而厚壁菌和绿屈菌以及原生动物根茎和变形虫在表层沉积物中的丰度高于其他两种介质。赋予生物膜形成或污染物去除的属（Cellvibrio、Chitinophaga、Ohtaekwangia和Uliginosibacterium）在附生生物膜中被检测到。网络分析结果表明，与上覆水和表层沉积物相比，附生生物膜中微生物之间的相互作用更为复杂。我们的研究结果强调 REC 可以是沉水植物的良好胁迫指标，而养分水平和空间变化引起的微生物群落差异可能被用作沉水植物主导水体水质的微生物指标。这些数据将为保护水生生态系统的最佳管理实践提供有用的信息。