摘要

    人们发现微塑料（MPs）无处不在，并且可以作为其他污染物的媒介，不可避免的老化过程会改变MP的特性和命运。但是，人们对衰老过程中的MPs是否会影响水生环境中抗生素抗性基因（ARGs）的命运知之甚少。在此，研究了垃圾渗滤液（MPs和ARGs的重要储藏库）中老化的MPs的理化性质变化，并分析了老化过程中MP表面微生物群落的演变和ARGs的发生。老化过程显着改变了表面性质，包括增加比表面积，导致形成含氧基团和改变表面形态，从而进一步增加了微生物定殖的可能性。与浸出液相比，MPs上的细菌聚集表现出更高的生物膜形成和致病性。 ARGs的定量结果表明，MP对ARGs表现出5.7-103倍的选择性富集，而时效过程增强了其富集潜力。进一步的共现网络表明，MP表面上存在非随机，更紧密和更稳定的ARGs-细菌类群关系会影响ARG的传播。对MPs上ARG分配的研究表明，细胞外DNA是附着在MP表面的ARGs不可忽略的储库，并且生物膜细菌群落在衰老过程中影响ARGs的分配方式。这项研究证实，衰老过程可以增强MPs作为ARGs载体的潜力，这将促进对MP行为和自然环境中的风险的全面了解。

    Microplastics (MPs) are found to be ubiquitous and serve as vectors for other contaminants, and the inevitable aging process changes MP properties and fates. However, whether the MPs in aging process affects the fates of antibiotic resistance gene (ARGs) in aquatic environments is poorly understood. Herein, the physicochemical property alteration of MPs being aged in landfill leachate, an important reservoir of MPs and ARGs, was investigated, and microbial community evolution and ARGs occurrence of MP surface during the aging process were analyzed. Aging process remarkably altered surface properties, including increasing specific surface areas, causing the formation of oxygen-containing groups, and changing surface morphology, which further increased the probability of microbial colonization. The bacterial assemblage on MPs showed higher biofilm-forming and pathogenic potential compared to leachate. ARGs quantification results suggested that MPs exhibited selective enrichment for ARGs in a ratio of 5.7–103 folds, and the aging process enhanced the enrichment potential. Further co-occurrence networks suggested that the existence of non-random, closer and more stable ARGs-bacterial taxa relations on MP surface affected the ARG transmission. The study of ARG partitioning on MPs indicated that extracellular DNA was a nonnegligible reservoir of ARGs attached on MP surface, and that biofilm bacterial community influenced ARGs partitioning pattern during the aging process. This study confirmed that the aging process could enhance the potential of MPs as vectors for ARGs, which would promote the holistic understanding of MP behavior and risk in natural environments.

    https://www.sciencedirect.com/science/article/abs/pii/S0269749120369670