摘要

       抗生素抗性细菌在自然环境中无处不在。将衍生的抗生素抗性基因 (ARG) 引入水生环境是遗传风险传播的一个问题。该研究表明，在南非河流和河口水及污水处理厂 (STP) 的总细菌组合和菌落形成细菌组合中，磺胺和四环素抗性基因 sul1、sul2、sul3 和 tet(M) 普遍存在。抗生素浓度和 ARGs 之间没有相关性，表明靶向 ARGs 分布在广泛的区域，与选择压力无关。在 sul 基因中，sul1 和 sul2 是总基因（超过 10-2 拷贝/16S）和菌落形成细菌组合（~10-1 拷贝/16S）中的主要基因。在城市水域中，sul3 基因在总的和可培养的组合中大多检测不到，这表明 sul3 并不丰富。 tet(M) 在 STP 中以 10-3 拷贝/16S 水平的天然组合中被发现，但在菌落形成细菌中未检测到，表明城市地表水和 STP 中存在不可培养（尚未培养）的细菌群落effluent 具有tet(M) 基因。城市水域中磺胺甲恶唑 (SMX) 抗性 (SMXr) 和土霉素 (OTC) 抗性 (OTCr) 细菌群落不仅具有 sul1 和 sul2，还具有 sul3 和 tet(M) 基因。这些基因广泛分布于 SMXr 和 OTCr 细菌中。总之，德班地区的城市河流和河口水和 STP 污水受到 ARGs 的高度污染，在某些情况下，尚未培养的细菌群落可能充当不可见的 ARG 库。

       Antibiotic resistant bacteria are ubiquitous in the natural environment. The introduction of effluent derived antibiotic resistance genes (ARGs) into aquatic environments is of concern in the spreading of genetic risk. This study showed the prevalence of sulfonamide and tetracycline resistance genes, sul1, sul2, sul3, and tet(M), in the total bacterial assemblage and colony forming bacterial assemblage in river and estuarine water and sewage treatment plants (STP) in South Africa. There was no correlation between antibiotic concentrations and ARGs, suggesting the targeted ARGs are spread in a wide area without connection to selection pressure. Among sul genes, sul1 and sul2 were major genes in the total (over 10-2 copies/16S) and colony forming bacteria assemblages (∼10-1 copies/16S). In urban waters, the sul3 gene was mostly not detectable in total and culturable assemblages, suggesting sul3 is not abundant. tet(M) was found in natural assemblages with 10-3 copies/16S level in STP, but was not detected in colony forming bacteria, suggesting the non-culturable (yet-to-be cultured) bacterial community in urban surface waters and STP effluent possess the tet(M) gene. Sulfamethoxazole (SMX) resistant (SMXr) and oxytetracycline (OTC) resistant (OTCr) bacterial communities in urban waters possessed not only sul1 and sul2 but also sul3 and tet(M) genes. These genes are widely distributed in SMXr and OTCr bacteria. In conclusion, urban river and estuarine water and STP effluent in the Durban area were highly contaminated with ARGs, and the yet-to-be cultured bacterial community may act as a non-visible ARG reservoir in certain situations.

https://www.frontiersin.org/articles/10.3389/fmicb.2015.00796/full