Dep. of Crop, Soil, and Environmental Sciences, 115 Plant Science Bldg., Univ. of Arkansas, Fayetteville, AR 72701, USA.
J Environ Qual. 2010 Nov-Dec;39(6):2211-5. doi: 10.2134/jeq2010.0228.
The occurrence of broad-host-range (BHR) plasmid amplicons belonging to incompatibility (Inc) groups IncA/C, IncN, IncP, and IncW in two wastewater treatment plant (WWTP) effluents and effluent-receiving streams in Northwest Arkansas, Mud Creek and Spring Creek, was determined. Community DNA captured on filter membranes and plasmid DNA extracted from antibiotic-resistant Escherichia coli isolated from Mud Creek was used for polymerase chain reaction at amplification of partial gene sequences specific to BHR plasmids. IncP plasmid amplicons were detected in effluent and downstream sites in both streams, while IncN and IncW plasmid amplicons were detected in Spring Creek in effluent and downstream but not upstream. IncA/C plasmid amplicons, in contrast, were detected at all sites, including upstream in most samples in Spring Creek and in one sample from Mud Creek. One IncP and two IncN were the only BHR plasmid amplicons found in 85 screened antibiotic-resistant E. coli isolates, and were detected only in isolates from effluent and downstream samples. Broad-host-range plasmids frequently carry antibiotic-resistance genes and can facilitate horizontal transfer of those genes. While BHR plasmids have been detected in WWTPs, WWTPs do not target these genetic elements for destruction. This study indicates that BHR plasmids are in WWTP effluent and are introducing BHR plasmids into streams. Additionally, species other than E. coli may be better targets as indicator bacteria for future studies of the impact of treated effluent on environmental dissemination of BHR plasmids.
在阿肯色州西北部的两个污水处理厂（WWTP）的出水和出水接收溪流—— Mud 溪和 Spring 溪中，确定了属于不相容性（Inc）组 IncA/C、IncN、IncP 和 IncW 的广泛宿主范围（BHR）质粒扩增子的存在。使用膜过滤器捕获的社区 DNA 和从 Mud 溪中分离的抗生素抗性大肠杆菌中提取的质粒 DNA，用于聚合酶链反应，以扩增 BHR 质粒的部分基因序列。在两个溪流的污水和下游地点都检测到了 IncP 质粒扩增子，而在 Spring 溪的污水和下游地点检测到了 IncN 和 IncW 质粒扩增子，但在上游没有检测到。相比之下，在 Spring 溪的大多数样本以及 Mud 溪的一个样本的所有地点都检测到了 IncA/C 质粒扩增子，包括上游。在 85 个筛选出的抗生素抗性大肠杆菌分离株中，仅发现了一个 IncP 和两个 IncN 是唯一的 BHR 质粒扩增子，并且仅在污水和下游样本的分离株中检测到。广泛宿主范围的质粒经常携带抗生素抗性基因，并能促进这些基因的水平转移。虽然 BHR 质粒已在 WWTP 中检测到，但 WWTP 并没有将这些遗传元件作为目标进行破坏。本研究表明，BHR 质粒存在于 WWTP 废水中，并将 BHR 质粒引入溪流。此外，与大肠杆菌相比，其他物种可能是未来研究处理后的废水对 BHR 质粒在环境中传播的影响的更好指示菌。
