CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China; USTC-CityU Joint Advanced Research Center, Suzhou Research Institute, University of Science and Technology of China, Suzhou, 215123, China.
CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
J Hazard Mater. 2021 Apr 15;408:124428. doi: 10.1016/j.jhazmat.2020.124428. Epub 2020 Oct 31.
Antibiotic resistance has been regarded as a global concern and biological wastewater treatment plants (WWTPs) are ideal hotbeds for the emergence and propagation of antibiotic resistance genes (ARGs). Extracellular polymeric substances (EPS), one of the primary components of activated sludge, might affect the distribution of extracellular ARGs in supernatant and EPS matrix, and thus alter their uptake potential by microbial cells. Herein, the presence and significance of EPS-associated ARGs in activated sludge from four WWTPs were assessed. Seven typical ARGs (sulI, sulII, bla, tetA, tetO, tetQ, tetW) and class I integron (intI1) in EPS-associated, cell-free, and intracellular DNA were quantified. Results show that the absolute abundances of EPS-associated, cell-free, and intracellular ARGs were 5.90 × 10-6.45 × 10, 5.53 × 10-4.58 × 10, and 2.68 × 10-1.79 × 10 copies/g-volatile suspended solids, respectively. The absolute abundances of EPS-associated ARGs were 0.2-4.6 orders of magnitude higher than those of the corresponding cell-free ARGs. Considering the higher DNA contents in EPS, the transformation abilities of EPS-associated ARGs were 3.3-236.3 folds higher than those of cell-free ARGs. Therefore, EPS-associated ARGs are an important source of extracellular ARGs, and it may play a crucial role in horizontal gene transfer via transformation in WWTPs.
抗生素耐药性已被视为全球性问题，而生物污水处理厂（WWTP）是抗生素耐药基因（ARGs）出现和传播的理想温床。细胞外聚合物（EPS）是活性污泥的主要成分之一，可能会影响细胞外 ARGs 在上清液和 EPS 基质中的分布，从而改变其被微生物细胞摄取的潜力。本文评估了来自四个 WWTP 的活性污泥中 EPS 相关 ARGs 的存在和意义。定量了 EPS 相关、无细胞和细胞内 DNA 中的七种典型 ARGs（sulI、sulII、bla、tetA、tetO、tetQ、tetW）和 I 类整合子（intI1）。结果表明，EPS 相关、无细胞和细胞内 ARGs 的绝对丰度分别为 5.90×10-6.45×10、5.53×10-4.58×10和 2.68×10-1.79×10 拷贝/g-挥发性悬浮固体。EPS 相关 ARGs 的绝对丰度比相应的无细胞 ARGs 高 0.2-4.6 个数量级。考虑到 EPS 中更高的 DNA 含量，EPS 相关 ARGs 的转化能力比无细胞 ARGs 高 3.3-236.3 倍。因此，EPS 相关 ARGs 是细胞外 ARGs 的重要来源，它可能在 WWTP 中通过转化在水平基因转移中发挥关键作用。
