College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China.
College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China.
J Hazard Mater. 2023 Oct 15;460:132350. doi: 10.1016/j.jhazmat.2023.132350. Epub 2023 Aug 19.
Microplastics (MPs) in the environment are always colonized by microbes, which may have implications for carrying effect of pollutants and exposure risk in organisms. We present the crucial impacts and mechanisms of microbial colonization on the bioaccessibility and toxicity of Pb(II) loaded in disposable box-derived polypropylene (PP) and polystyrene (PS) MPs and montmorillonite (MMT) clay particles. After 45 d incubation, higher biomass measured by crystal violet staining were detected in MMT (1.23) than in PP and PS (0.400 and 0.721) indicating preferential colonization of microbes in clay particles. Microbial colonization further enhanced the sorption ability toward Pb(II), but inhibited the desorption and bioaccessibility of enriched Pb(II) in zebrafish and decreased the toxicity to gastric epithelial cells in an order of MMT > PS ≈ PP. The crucial effects were mainly because microbe-colonized substrates possessed higher oxygen functional groups and specific surface area and exhibited stronger interactions with Pb(II) and digestive component (i.e., pepsin) than pure substrates. This decreased the available soluble pepsin for complexing with sorbed Pb(II). The findings highlight the role of microbial colonization in modulating the exposure risks of artificial and natural substrate-associated pollutants and suggest that the risks of MPs may be overestimated compared to clay particles.
环境中的微塑料（MPs）总是被微生物定殖，这可能对污染物的携带效应和生物体的暴露风险有影响。我们介绍了微生物定殖对可生物利用性和毒性的关键影响和机制，这些影响和机制涉及到负载 Pb(II) 的一次性盒衍生聚丙烯（PP）和聚苯乙烯（PS） MPs 以及蒙脱石（MMT）粘土颗粒。经过 45 天的孵育，结晶紫染色测量的生物量更高，表明微生物在粘土颗粒中优先定殖。微生物定殖进一步增强了对 Pb(II)的吸附能力，但抑制了斑马鱼中富集 Pb(II)的解吸和生物可利用性，并按 MMT > PS ≈ PP 的顺序降低了对胃上皮细胞的毒性。关键影响主要是因为微生物定殖的基质具有更高的含氧官能团和比表面积，并与 Pb(II)和消化成分（即胃蛋白酶）表现出更强的相互作用，而不是纯基质。这减少了可用于与吸附的 Pb(II)络合的可溶性胃蛋白酶。研究结果强调了微生物定殖在调节人工和天然基质相关污染物暴露风险方面的作用，并表明与粘土颗粒相比， MPs 的风险可能被高估。
