Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Water Res. 2022 Aug 15;222:118899. doi: 10.1016/j.watres.2022.118899. Epub 2022 Jul 26.
The ubiquitous microplastics (MPs) in water environment play an important role in the dissemination of antibiotic resistance genes (ARGs) due to their exchange between floating MPs and receiving waters. However, whether the ARG exchange is persistent or transient and what are the differences in ARG exchange between conventional plastics and biodegradable plastics are the two key issues to be addressed. In this study, biodegradable PBAT and non-biodegradable PET MPs were chosen to explore the MP-water ARG exchange after the MPs floated to the receiving waters. The results demonstrated that the active exchange of ARGs between MPs and receiving waters occurred, which, however, were transient for most of ARGs. The relative abundance of ARGs both on the MPs and in the waters rapidly decreased to the initial or lower levels within 4 weeks. Approximately 25-50% (ARG subtype number ratio) of studied ARG subtypes were introduced into the receiving waters by MPs, and 35-65% of studied ARG subtypes went through fluctuation in terms of abundance on MPs and in the receiving water. ARGs tended to converge between MPs and the receiving waters with time. Furthermore, the ARG exchange between MPs and waters facilitated horizontal gene transfer (HGT). IntI1 and tnpA05 played the crucial roles in HGT, which was indicated by their correlated change with most ARGs; in contrast, tnpA04 showed the obvious lagging responses. The biodegradable MP of PBAT generally accumulated higher levels of most ARGs including multidrug resistant genes than the non-biodegradable MP of PET. The transient exchange of most ARGs between MPs and water implies that the on-off hitchhiking of ARGs on MPs in aquatic environment may not exert significant influence on ARG transmission. However, compared with the conventional plastics, the biodegradable MPs might pose much higher ARG dissemination risks due to the higher enrichment of ARGs particularly with people's ever-increasingly usage. Enough attention must be paid to this emerging issue.
水环境中无处不在的微塑料（MPs）由于其在浮 MPs 和受纳水体之间的交换，在抗生素耐药基因（ARGs）的传播中起着重要作用。然而，ARGs 的交换是持久的还是瞬时的，以及传统塑料和可生物降解塑料之间的 ARG 交换有何不同，是两个需要解决的关键问题。在这项研究中，选择了可生物降解的 PBAT 和不可生物降解的 PET MPs，以探索 MPs 漂浮到受纳水体后 MPs-水 ARG 的交换。结果表明，MPs 和受纳水体之间发生了 ARGs 的主动交换，但大多数 ARGs 的交换是瞬时的。在 4 周内，MPs 上和水中的 ARGs 的相对丰度迅速下降到初始或更低水平。大约 25-50%（ARG 亚型数量比）的研究 ARG 亚型通过 MPs 被引入受纳水体，而 35-65%的研究 ARG 亚型在 MPs 和受纳水体中的丰度上经历了波动。随着时间的推移，ARGs 趋于在 MPs 和受纳水体之间收敛。此外，MPs 和水体之间的 ARG 交换促进了水平基因转移（HGT）。IntI1 和 tnpA05 在 HGT 中起着关键作用，这表明它们与大多数 ARGs 的相关性变化；相比之下，tnpA04 显示出明显的滞后反应。与不可生物降解的 PET MPs 相比，可生物降解的 PBAT MPs 通常会积累更多的 ARGs，包括多药耐药基因。MPs 和水体之间大多数 ARGs 的瞬时交换意味着 ARGs 在水生环境中 MPs 上的开-关搭便车可能不会对 ARG 传播产生显著影响。然而，与传统塑料相比，由于可生物降解 MPs 的 ARGs 富集程度更高，特别是随着人们使用量的不断增加，可生物降解 MPs 可能会带来更高的 ARG 传播风险。必须对这一新兴问题给予足够的重视。
