摘要
      微塑料（MPs）越来越多地进入城市水生生态系统，塑料层作为MPs上的一种特殊生物膜，其环境意义和健康风险受到了广泛关注。在本研究中，聚乳酸（PLA）、聚氯乙烯（PVC）和石英岩的MPs在城市水环境中孵育，并比较了四环素（TC）的降解能力。在水-石英岩系统中，约24%的TC在28天内生物降解，显著高于水-聚乳酸（17.3%）和水-聚氯乙烯系统（16.7%）。生物膜中微生物的再培养证实石英岩生物膜比塑料层具有更高的TC降解能力。根据16S rRNA的高通量测序和宏基因组分析，石英岩生物膜含有更丰富的潜在TC降解细菌、与TC降解相关的基因（eutG、aceE和DLAT）以及与TC降解有关的代谢途径。石英岩表面的贫营养环境可能导致石英岩生物膜对非常规碳（如TC）具有更高的代谢能力。研究还发现，与石英岩生物薄膜相比，质体中不同的微生物携带更多的抗生素抗性基因（ARGs）。MPs表面对抗生素的亲和力越高，可能会导致质体受到更高的抗生素应力，从而进一步增强质体中微生物对ARGs的携带能力。与不可降解的PVC MPs相比，可生物降解的PLA塑料表面含有显著更高量的生物质和ARGs。与矿物颗粒相比，由于MPs表面丰富的碳源（吸附有机碳和内源性有机碳），塑性球体降解难降解有机污染物等非常规碳源的能力较低。同时，对污染物更强的吸附能力也会导致质体中更高的污染物胁迫（如抗生素胁迫），进而影响质体本身的微生物特性，如携带更多的ARG。
Abstract
Microplastics (MPs) are increasingly entering the urban aquatic ecosystems, and the environmental significance and health risks of plastisphere, a special biofilm on MPs, have received widespread attention. In this study, MPs of polylactic acid (PLA) and polyvinyl chloride (PVC) and quartzite were incubated in an urban water environment, and the tetracycline (TC) degradation ability was compared. Approximatedly 24% of TC biodegraded in 28 d in the water-quartzite system, which is significantly higher than that in the water-PLA (17.3%) and water-PVC systems (16.7%). Re-incubation of microorganisms in biofilms affirmed that quartzite biofilm has a higher TC degradation capacity than the plastisphere. According to high-throughput sequencing of 16S rRNA and metagenomic analysis, quartzite biofilm contained more abundant potential TC degrading bacteria, genes related to TC degradation (eutG, aceE, and DLAT), and metabolic pathways related to TC degradation. An oligotrophic environment on the quartzite surface might lead to the higher metabolic capacity of quartzite biofilm for unconventional carbons, e.g., TC. It is also found that, compared with quartzite biofilm, the distinct microbes in the plastisphere carried more antibiotic resistance genes (ARGs). Higher affinity of MPs surface to antibiotics may lead to higher antibiotics stress on the plastisphere, which further amplify the carrying capacity for ARGs of microorganisms in the plastisphere. Compared to the nondegradable PVC MPs, surface of the biodegradable PLA plastics harbored significantly higher amounts of biomass and ARGs. Compared to the mineral particles, the capability of plastisphere has lower ability to degrade unconventional carbon sources such as the refractory organic pollutants, due to the abundance of carbon sources (adsorbed organic carbon and endogenous organic carbon) on the MPs surface. Meanwhile, the stronger adsorption capacity for pollutants also leads to higher pollutant stress (such as antibiotic stress) in plastisphere, which in turn affects the microbiological characteristics of the plastisphere itself, such as carrying more ARGs.

https://www.sciencedirect.com/science/article/abs/pii/S0043135422008673