Department of Biology, Loyola University Chicago, Chicago, Illinois, United States of America.
Illinois Sustainable Technology Center, Prairie Research Institute, Champaign, Illinois, United States of America.
PLoS One. 2021 Jan 6;16(1):e0244443. doi: 10.1371/journal.pone.0244443. eCollection 2021.
Microplastics are ubiquitous contaminants in aquatic habitats globally, and wastewater treatment plants (WWTPs) are point sources of microplastics. Within aquatic habitats microplastics are colonized by microbial biofilms, which can include pathogenic taxa and taxa associated with plastic breakdown. Microplastics enter WWTPs in sewage and exit in sludge or effluent, but the role that WWTPs play in establishing or modifying microplastic bacterial assemblages is unknown. We analyzed microplastics and associated biofilms in raw sewage, effluent water, and sludge from two WWTPs. Both plants retained >99% of influent microplastics in sludge, and sludge microplastics showed higher bacterial species richness and higher abundance of taxa associated with bioflocculation (e.g. Xanthomonas) than influent microplastics, suggesting that colonization of microplastics within the WWTP may play a role in retention. Microplastics in WWTP effluent included significantly lower abundances of some potentially pathogenic bacterial taxa (e.g. Campylobacteraceae) compared to influent microplastics; however, other potentially pathogenic taxa (e.g. Acinetobacter) remained abundant on effluent microplastics, and several taxa linked to plastic breakdown (e.g. Klebsiella, Pseudomonas, and Sphingomonas) were significantly more abundant on effluent compared to influent microplastics. These results indicate that diverse bacterial assemblages colonize microplastics within sewage and that WWTPs can play a significant role in modifying the microplastic-associated assemblages, which may affect the fate of microplastics within the WWTPs and the environment.
微塑料是全球水生栖息地中普遍存在的污染物，而废水处理厂（WWTP）是微塑料的一个点源。在水生栖息地中，微塑料被微生物生物膜所定殖，这些生物膜可能包括病原生物和与塑料降解有关的生物。微塑料通过污水进入 WWTP，并以污泥或废水的形式排出，但 WWTP 在建立或改变微塑料细菌组合方面的作用尚不清楚。我们分析了来自两个 WWTP 的原污水、出水和污泥中的微塑料和相关生物膜。这两个工厂都将超过 99%的进水微塑料保留在污泥中，而污泥中的微塑料具有更高的细菌物种丰富度和更高的与生物絮凝相关的生物（例如黄单胞菌）的丰度，这表明 WWTP 内微塑料的定殖可能在保留方面发挥作用。WWTP 废水中的微塑料中一些潜在的病原细菌的丰度明显低于进水微塑料（例如弯曲杆菌科）；然而，其他潜在的病原生物（例如不动杆菌）仍然在废水微塑料上丰富存在，并且与塑料降解相关的几个生物（例如克雷伯氏菌、假单胞菌和鞘氨醇单胞菌）在废水中的丰度明显高于进水微塑料。这些结果表明，不同的细菌组合定殖于污水中的微塑料，而 WWTP 可以在改变微塑料相关组合方面发挥重要作用，这可能会影响微塑料在 WWTP 内和环境中的命运。
