Amos G C A, Zhang L, Hawkey P M, Gaze W H, Wellington E M
School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.
Health Protection Agency, West Midlands Public Health Laboratory, Heart of England NHS Foundation Trust, Bordesley Green East, Birmingham, United Kingdom; Institute of Microbiology and Infection, Biosciences, University of Birmingham, Birmingham, United Kingdom.
Vet Microbiol. 2014 Jul 16;171(3-4):441-7. doi: 10.1016/j.vetmic.2014.02.017. Epub 2014 Feb 16.
The environment harbours a significant diversity of uncultured bacteria and a potential source of novel and extant resistance genes which may recombine with clinically important bacteria disseminated into environmental reservoirs. There is evidence that pollution can select for resistance due to the aggregation of adaptive genes on mobile elements. The aim of this study was to establish the impact of waste water treatment plant (WWTP) effluent disposal to a river by using culture independent methods to study diversity of resistance genes downstream of the WWTP in comparison to upstream. Metagenomic libraries were constructed in Escherichia coli and screened for phenotypic resistance to amikacin, gentamicin, neomycin, ampicillin and ciprofloxacin. Resistance genes were identified by using transposon mutagenesis. A significant increase downstream of the WWTP was observed in the number of phenotypic resistant clones recovered in metagenomic libraries. Common β-lactamases such as blaTEM were recovered as well as a diverse range of acetyltransferases and unusual transporter genes, with evidence for newly emerging resistance mechanisms. The similarities of the predicted proteins to known sequences suggested origins of genes from a very diverse range of bacteria. The study suggests that waste water disposal increases the reservoir of resistance mechanisms in the environment either by addition of resistance genes or by input of agents selective for resistant phenotypes.
环境中存在大量未培养细菌，是新出现的和现存抗性基因的潜在来源，这些基因可能与传播到环境储库中的临床重要细菌发生重组。有证据表明，由于适应性基因在移动元件上的聚集，污染可导致抗性选择。本研究的目的是通过使用非培养方法研究污水处理厂（WWTP）下游与上游相比抗性基因的多样性，来确定污水处理厂废水排放对河流的影响。在大肠杆菌中构建宏基因组文库，并筛选对阿米卡星、庆大霉素、新霉素、氨苄青霉素和环丙沙星的表型抗性。通过转座子诱变鉴定抗性基因。在宏基因组文库中回收的表型抗性克隆数量在污水处理厂下游显著增加。回收了常见的β-内酰胺酶如blaTEM，以及多种乙酰转移酶和不寻常的转运蛋白基因，有证据表明出现了新的抗性机制。预测蛋白质与已知序列的相似性表明这些基因来源于非常多样的细菌。该研究表明，废水处理要么通过添加抗性基因，要么通过输入对抗性表型有选择性的因子，增加了环境中抗性机制的储备。
