Objective: To explore the changes in bacterial community structure, antibiotic resistance genome, and pathogen virulence genome in river water before and after the river flowing through Haikou City and their transmission and dispersal patterns and to reveal anthropogenic disturbance's effects on microorganisms and resistance genes in the aquatic environment. Methods: The Nandu River was divided into three study areas: the front, middle and rear sections from the upstream before it flowed through Haikou City to the estuary. Three sampling sites were selected in each area, and six copies of the sample were collected in parallel at each site and mixed for 3 L per sample. Microbial community structure, antibiotic resistance, virulence factors, and mobile genetic elements were analyzed through bioinformatic data obtained by metagenomic sequencing and full-length sequencing of 16S rRNA genes. Variations in the distribution of bacterial communities between samples and correlation of transmission patterns were analyzed by principal co-ordinates analysis, procrustes analysis, and Mantel test. Results: As the river flowed through Haikou City, microbes' alpha diversity gradually decreased. Among them, Proteobacteria dominates in the bacterial community in the front, middle, and rear sections, and the relative abundance of Proteobacteria in the middle and rear sections was higher than that in the front segment. The diversity and abundance of antibiotic resistance genes, virulence factors, and mobile genetic elements were all at low levels in the front section and all increased significantly after flow through Haikou City. At the same time, horizontal transmission mediated by mobile genetic elements played a more significant role in the spread of antibiotic-resistance genes and virulence factors. Conclusions: Urbanization significantly impacts river bacteria and the resistance genes, virulence factors, and mobile genetic elements they carry. The Nandu River in Haikou flows through the city, receiving antibiotic-resistant and pathogen-associated bacteria excreted by the population. In contrast, antibiotic-resistant genes and virulence factors are enriched in bacteria, which indicates a threat to environmental health and public health. Comparison of river microbiomes and antibiotic resistance genomes before and after flow through cities is a valuable early warning indicator for monitoring the spread of antibiotic resistance.
目的： 探讨河流流经海口市前后河水中细菌菌群结构、抗生素耐药基因组和病原菌毒力基因组的变化，及其传播扩散模式。 方法： 从流经海口市前的南渡江上游至南渡江入海口划分前、中、后段3个研究区域，每个区域选择3个采样点，每个采样点平行采集6份样本并混合为1份，每份3 L。通过宏基因组测序和16S rRNA基因全长测序获得相关生物信息数据，分析前、中、后3段水体中微生物群落结构以及耐药基因、毒力因子和可移动遗传元件信息。运用主坐标分析、普氏分析和曼特尔检测等方法分析样本间菌群分布差异以及传播模式相关性。 结果： 随着河水流经海口市，微生物的α多样性呈现逐渐降低趋势。其中变形菌门在前、中、后段的细菌群落中均占据主导地位，中、后段变形菌门相对丰度高于前段。抗生素耐药基因、毒力因子及可移动遗传元件的多样性和丰度在前段均处于较低水平，流经海口市后，均明显升高。同时，可移动遗传元件介导的水平传播在抗生素耐药基因和毒力因子扩散中发挥较大作用。 结论： 城市化对河流中的微生物及其携带的耐药基因、毒力因子和可移动遗传元件产生显著影响。在海口市南渡江，河流流经城市受纳了人群排出的抗生素耐药菌和病原相关细菌，同时抗生素耐药基因和毒力因子在细菌中的富集，显示了城市人群排出的抗生素耐药菌和病原菌对环境健康和公共卫生的威胁。流经城市前后微生物组和抗生素耐药基因组的比较，也可成为有价值的抗生素耐药扩散监测预警指标。.