State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Environ Sci Technol. 2023 Nov 7;57(44):16788-16799. doi: 10.1021/acs.est.3c04097. Epub 2023 Oct 28.
Recently, studies have highlighted the potential danger for soil organisms posed by film-derived microplastics (MPs). However, the majority of those does not accurately reflect the field conditions and the degree of MP contamination that can be found in actual settings. To fill the gap between laboratory and field scenarios, the polyethylene (PE) plastic film was made into PE-MPs and aged. Toxicity and molecular mechanisms of pristine PE-MPs (PMPs) and aged PE-MPs (AMPs) with the concentration at 500 mg/kg of dry weight were determined after 14 days of exposure by measuring the oxidative stress, osmoregulation pressure, gut microbiota, and metabolic responses in earthworms under environmentally relevant conditions. Our research showed that, when compared to PMPs (13.13 ± 1.99 items/g), AMPs accumulated more (16.19 ± 8.47 items/g), caused more severe tissue lesions, and caused a higher increase of cell membrane osmotic pressure in earthworms' intestines. Furthermore, the proportion of probiotic bacteria in the gut bacterial communities was 24.26%, 23.26%, and 12.96%, while the proportion of pathogenic bacteria of the phylum Verrucomicrobia was 2.28%, 4.79%, and 10.39% in the control and PMP- and AMP-exposed earthworms, indicating that the decrease in number of probiotic bacteria and the increase in number of pathogenic bacteria were more pronounced in the gut of AMP- rather than PMP-exposed earthworms. Metabolomic analysis showed that AMP exposure reduced earthworm energy metabolites. Consequently, the constant need for energy may result in protein catabolism, which raises levels of some amino acids, disturbs normal cell homeostasis, causes changes of cell membrane osmolarity, and destroys the cell structure. Our studies showed that aged MPs, with the same characteristics as those found in the environment, have greater toxicity than pristine MPs. The results of this study broaden our understanding of the toxicological effects of MPs on soil organisms under environmentally relevant conditions.
最近的研究强调了薄膜衍生的微塑料（MPs）对土壤生物的潜在危险。然而，大多数研究并未准确反映野外条件和实际环境中发现的 MP 污染程度。为了填补实验室和野外场景之间的差距，将聚乙烯（PE）塑料薄膜制成 PE-MPs 并进行老化。在环境相关条件下，通过测量氧化应激、渗透调节压力、肠道微生物群和代谢反应，在 14 天的暴露后，确定浓度为 500mg/kg 干重的原始 PE-MPs（PMPs）和老化 PE-MPs（AMPs）的毒性和分子机制。我们的研究表明，与 PMPs（13.13±1.99 项/g）相比，AMPs 积累更多（16.19±8.47 项/g），对组织造成更严重的损伤，并导致蚯蚓肠道细胞膜渗透压升高更高。此外，肠道细菌群落中益生菌的比例分别为 24.26%、23.26%和 12.96%，而控制组和 PMP 和 AMP 暴露的蚯蚓中厚壁菌门致病性细菌的比例分别为 2.28%、4.79%和 10.39%，这表明益生菌数量减少和致病菌数量增加在 AMP 暴露的蚯蚓肠道中更为明显，而不是 PMP 暴露的蚯蚓肠道。代谢组学分析表明，AMP 暴露降低了蚯蚓的能量代谢物。因此，对能量的持续需求可能导致蛋白质分解代谢，从而提高某些氨基酸的水平，扰乱正常的细胞内稳态，改变细胞膜渗透压，并破坏细胞结构。我们的研究表明，具有与环境中发现的特征相同的老化 MPs 比原始 MPs 具有更大的毒性。这项研究的结果拓宽了我们对在环境相关条件下 MPs 对土壤生物的毒理学影响的理解。
