Civil Engineering Department, New Mexico State University, Las Cruces, NM, 88003, USA.
Biology Department, New Mexico State University, Las Cruces, NM, 88003, USA.
Chemosphere. 2021 May;271:129563. doi: 10.1016/j.chemosphere.2021.129563. Epub 2021 Jan 7.
The aim of this study was to evaluate the impacts of conventional wastewater treatment processes including secondary treatment and chlorination on the removal of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB), and to assess the association of ARGs with their potential hosts in each treatment process. The results showed chlorination with subinhibitory concentration (<8 mg/L) resulted in an increased ARB number in the disinfection effluent. qPCR analysis indicated secondary treatment increased relative abundance of ARGs in remaining bacteria whereas disinfection reduced the relative abundance of those genes effectively. Metagenomic analysis revealed a significant shift of dominating bacterial genera harboring ARGs. Along the treatment train, 48, 95 and 80 genera were identified to be the ARG carriers in primary effluent, secondary effluent, and disinfection effluent, respectively. It was also found that secondary treatment increased the diversity of potential ARG hosts while both secondary treatment and chlorination broadened the host range of some ARGs at the genus level, which may be attributed to the spread of antibiotic resistance across bacterial genera through horizontal transfer. This study highlights the growing concerns that wastewater treatment plants (WWTPs) may disseminate ARGs by associating this effect to specific treatment stages and by correlating ARGs with their bacterial hosts.
本研究旨在评估传统污水处理工艺（包括二级处理和氯化消毒）对去除抗生素耐药基因（ARGs）和抗生素耐药菌（ARB）的影响，并评估 ARGs 与其在每个处理过程中的潜在宿主的关联。结果表明，亚抑菌浓度（<8mg/L）的氯化消毒会导致消毒出水中 ARB 数量增加。qPCR 分析表明，二级处理增加了剩余细菌中 ARGs 的相对丰度，而消毒则有效地降低了这些基因的相对丰度。宏基因组分析显示，具有 ARGs 的优势细菌属发生了显著变化。沿处理链，在原水、二级出水和消毒出水中，分别鉴定出 48、95 和 80 个属为 ARG 载体。研究还发现，二级处理增加了潜在 ARG 宿主的多样性，而二级处理和氯化消毒均拓宽了一些 ARGs 在属水平上的宿主范围，这可能归因于抗生素耐药性通过水平转移在细菌属间传播。本研究强调了污水处理厂（WWTPs）可能通过将这种效应与特定处理阶段相关联，并将 ARGs 与其细菌宿主相关联，从而传播 ARGs 的日益关注。
