School of Biological Sciences, University of Utah, 257 South 1400 East, Rm. 201, 84112, Salt Lake City, UT, USA.
Department of Family and Preventive Medicine, University of Utah, 257 South 1400 East, Rm. 201, 84112, Salt Lake City, UT, USA.
Gigascience. 2020 Nov 19;9(11). doi: 10.1093/gigascience/giaa125.
Wastewater treatment is an essential tool for maintaining water quality in urban environments. While the treatment of wastewater can remove most bacterial cells, some will inevitably survive treatment to be released into natural environments. Previous studies have investigated antibiotic resistance within wastewater treatment plants, but few studies have explored how a river's complete set of antibiotic resistance genes (the "resistome") is affected by the release of treated effluent into surface waters.
Here we used high-throughput, deep metagenomic sequencing to investigate the effect of treated wastewater effluent on the resistome of an urban river and the downstream distribution of effluent-associated antibiotic resistance genes and mobile genetic elements. Treated effluent release was found to be associated with increased abundance and diversity of antibiotic resistance genes and mobile genetic elements. The impact of wastewater discharge on the river's resistome diminished with increasing distance from effluent discharge points. The resistome at river locations that were not immediately downstream from any wastewater discharge points was dominated by a single integron carrying genes associated with resistance to sulfonamides and quaternary ammonium compounds.
Our study documents variations in the resistome of an urban watershed from headwaters to a major confluence in an urban center. Greater abundances and diversity of antibiotic resistance genes are associated with human fecal contamination in river surface water, but the fecal contamination effect seems to be localized, with little measurable effect in downstream waters. The diverse composition of antibiotic resistance genes throughout the watershed suggests the influence of multiple environmental and biological factors.
污水处理是维护城市环境水质的重要手段。尽管污水处理可以去除大部分细菌细胞，但仍有一些不可避免地会在处理后存活并释放到自然环境中。先前的研究已经调查了污水处理厂中的抗生素耐药性，但很少有研究探索经过处理的污水排放到地表水后如何影响整条河流的整套抗生素耐药基因（“耐药组”）。
在这里，我们使用高通量、深度宏基因组测序来研究处理后的废水对城市河流耐药组以及下游废水中抗生素耐药基因和移动遗传元件分布的影响。发现处理后的污水排放与抗生素耐药基因和移动遗传元件的丰度和多样性增加有关。随着与污水排放点距离的增加，污水排放对河流耐药组的影响减小。距离任何污水排放点都没有直接下游的河流位置的耐药组主要由一个整合子组成，该整合子携带与磺胺类和季铵化合物耐药相关的基因。
我们的研究记录了城市流域从源头到城市中心主要汇合处的耐药组的变化。河流水体中抗生素耐药基因的丰度和多样性与人类粪便污染有关，但粪便污染的影响似乎是局部的，下游水体几乎没有可测量的影响。整个流域中抗生素耐药基因的多样组成表明受到多种环境和生物因素的影响。
