State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, 200092 Shanghai, PR China.
Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, New South Wales 2007, Australia.
Environ Sci Technol. 2023 Oct 3;57(39):14611-14621. doi: 10.1021/acs.est.3c02815. Epub 2023 Sep 21.
Antibiotic resistance genes (ARGs) and microplastics (MPs) are recognized as emerging contaminants and threats to global human health. Despite both of them being significantly detected in their "hotspots", i.e., waste activated sludge (WAS), rare studies on how MPs affect ARGs and antibiotic-resistant bacteria (ARB) in anaerobic sludge digestion are available. Herein, the fate of ARGs and ARB after exposure to MPs of three dosages (10, 30, and 80 particles/g-TS), three polymer types (LDPE, PET, and PS), and three branching extents (LDPE, LLDPE, and HDPE) in anaerobic sludge digestion was investigated. Metagenomic results indicated that all variants of MPs resulted in an increase of the relative abundance of ARGs in the digester compared to the control. The abundance of ARGs demonstrated a dosage-dependent relationship within the range from 10 to 80 particles/g-TS, resulting in an increase from 4.5 to 27.9% compared to the control. Branching structure and polymer type influence ARG level in the sludge digester as well. Mechanism studies revealed that LDPE selectively enriched potential ARB and ARGs in the surface biofilm, possibly creating a favorable environment for ARB proliferation and ARG exchange. Furthermore, vertical transfer of ARGs was facilitated by LDPE through increasing bacterial cell proliferation accompanied by the enhancement of relevant functional genes. The elevated abundance of mobile genetic elements (MGEs) and ARGs-carrying plasmids also demonstrated that MGE-mediated horizontal transfer was promoted by LDPE at 80 particles/g-TS. This effect was compounded by increased oxidative stress, cell membrane permeability, and cell cohesion, collectively facilitating horizontal ARG transfer. Consequently, both vertical and horizontal transfer of ARGs could be concurrently promoted by LDPE an in anaerobic sludge digester.
抗生素耐药基因（ARGs）和微塑料（MPs）被认为是新兴的污染物，对全球人类健康构成威胁。尽管它们都在其“热点”，即废活性污泥（WAS）中被显著检测到，但关于 MPs 如何影响厌氧污泥消化中 ARGs 和抗生素耐药细菌（ARB）的研究很少。在此，研究了在厌氧污泥消化中，暴露于三种剂量（10、30 和 80 个颗粒/g-TS）、三种聚合物类型（LDPE、PET 和 PS）和三种支化程度（LDPE、LLDPE 和 HDPE）的 MPs 后 ARGs 和 ARB 的命运。宏基因组学结果表明，与对照组相比，所有 MPs 变体都导致消化器中 ARGs 的相对丰度增加。在 10 至 80 个颗粒/g-TS 的范围内，丰度与剂量呈依赖性关系，与对照组相比，增加了 4.5 至 27.9%。支化结构和聚合物类型也会影响污泥消化器中的 ARG 水平。机制研究表明，LDPE 选择性地在表面生物膜中富集潜在的 ARB 和 ARGs，可能为 ARB 的增殖和 ARG 的交换创造有利的环境。此外，LDPE 通过增加与相关功能基因相关的细菌细胞增殖来促进 ARGs 的垂直转移。移动遗传元件（MGEs）和携带 ARGs 的质粒的丰度增加也表明，LDPE 在 80 个颗粒/g-TS 时促进了 MGE 介导的水平转移。这种效应与氧化应激、细胞膜通透性和细胞内聚力的增加有关，这些因素共同促进了水平 ARG 转移。因此，LDPE 可以在厌氧污泥消化器中同时促进 ARGs 的垂直和水平转移。
