Rivers and lakes are used for multiple purposes such as for drinking water (DW) production, recreation, and as recipients of wastewater from various sources. The deterioration of surface water quality with wastewater is well-known, but less is known about the bacterial community dynamics in the affected surface waters. Understanding the bacterial community characteristics —from the source of contamination, through the watershed to the DW production process—may help safeguard human health and the environment. The spatial and seasonal dynamics of bacterial communities, their predicted functions, and potential health-related bacterial (PHRB) reads within the Kokemäenjoki River watershed in southwest Finland were analyzed with the 16S rRNA-gene amplicon sequencing method. Water samples were collected from various sampling points of the watershed, from its major pollution sources (sewage influent and effluent, industrial effluent, mine runoff) and different stages of the DW treatment process (pre-treatment, groundwater observation well, DW production well) by using the river water as raw water with an artificial groundwater recharge (AGR). The beta-diversity analysis revealed that bacterial communities were highly varied among sample groups (R = 0.92, p < 0.001, ANOSIM). The species richness and evenness indices were highest in surface water (Chao1; 920 ± 10) among sample groups and gradually decreased during the DW treatment process (DW production well; Chao1: 320 ± 20). Although the phylum Proteobacteria was omnipresent, its relative abundance was higher in sewage and industrial effluents (66–80%) than in surface water (55%). Phyla Firmicutes and Fusobacteria were only detected in sewage samples. Actinobacteria was more abundant in the surface water (≥13%) than in other groups (≤3%). Acidobacteria was more abundant in the DW treatment process (≥13%) than in others (≤2%). In total, the share of PHRB reads was higher in sewage and surface water than in the DW treatment samples. The seasonal effect in bacterial communities was observed only on surface water samples, with the lowest diversity during summer. The low bacterial diversity and absence of PHRB read in the DW samples indicate AGR can produce biologically stable and microbiologically safe drinking water. Furthermore, the significantly different bacterial communities at the pollution sources compared to surface water and DW samples highlight the importance of effective wastewater treatment for protecting the environment and human health.

中文翻译：

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多功能地表水系统中的细菌多样性和预期的酶功能-从废水排放到饮用水生产

河流和湖泊有多种用途，例如用于饮用水（DW）的生产，娱乐以及各种来源废水的接收。废水使地表水质量下降的情况众所周知，但对受影响地表水中细菌群落动态的了解却很少。了解细菌群落特征-从污染源到分水岭到DW生产过程-可能有助于维护人类健康和环境。使用16S rRNA基因扩增子测序方法分析了芬兰西南部Kokemäenjoki河流域内细菌群落的空间和季节动态，其预测功能以及与健康相关的潜在细菌（PHRB）读数。从流域的各个采样点收集水样，通过使用河水作为人工水和人工地下水，从其主要污染源（污水和污水，工业废水，矿山径流）和DW处理过程的不同阶段（预处理，地下水观测井，DW生产井）充值（AGR）。β多样性分析表明，样品组之间的细菌群落差异很大（R = 0.92，p <0.001，ANOSIM）。样品组中地表水的物种丰富度和均匀度指数最高（Chao1； 920±10），在DW处理过程中（DW生产井； Chao1：320±20）逐渐降低。尽管Proteobacteria门无处不在，但其相对丰度在污水和工业废水中（66-80％）要比地表水（55％）要高。仅在污水样品中检测到了疫霉菌和梭菌。地表水中的放线菌比其他组（≤3％）丰富（≥13％）。在DW处理过程中，酸性细菌（≥13％）比其他细菌（≤2％）丰富。总体而言，污水和地表水中的PHRB读数比DW处理样品高。仅在地表水样品上观察到细菌群落的季节性影响，夏季的多样性最低。DW样品中细菌多样性低且没有PHRB读数，表明AGR可以产生生物稳定和微生物安全的饮用水。此外，