Characterization of biofilms formed on polystyrene microplastics (PS-MPs) on the shore of the Tuul River, Mongolia
Characterization of biofilms formed on polystyrene microplastics (PS-MPs) on the shore of the Tuul River, Mongolia
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DOI：
10.1016/j.envres.2022.113329
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发表时间：
2022-05-09
影响因子：
8.3
通讯作者：
Oyuntsetseg, Bolormaa
中科院分区：
文献类型：
--
作者：
Battulga, Batdulam;Kawahigashi, Masayuki;Oyuntsetseg, Bolormaa
微塑料 (MP) 表面是微生物定植的常见场所，可促进水生环境中生物膜的形成，从而导致 MP 表面特性及其与污染物相互作用的变化。尽管在水生环境中附着在 MP 上的微生物群落的多样性已得到充分记录，但由于微生物定植而导致的 MP 表面变化仍然知之甚少。在这项研究中，我们旨在利用微傅里叶变换红外（micro-FTIR）光谱评估从蒙古图拉河沿岸收集的聚苯乙烯微塑料（PS-MP）表面的化学结构和生物膜成分的变化。我们应用了光谱减法方法，过氧化物处理和未处理的 PS-MP 颗粒之间的光谱差异使我们能够获得塑料表面上形成的生物膜的结构特征。此外，通过过氧化物处理和原始 PS-MP 的减差光谱计算了采样的 PSMP 的表面光氧化状态。在获得的生物膜光谱中检测到来自细菌和真菌群落的含氮有机物质的各种官能团。根据光谱特征，通过应用主成分分析（PCA）将生物膜光谱分为四组。在过氧化物处理和原始 PS-MP 之间的减色光谱中发现了广泛的羰基指数 (CI: 0.00-1.40)，这表明太阳辐射和冻融循环等物理影响导致了不同程度的表面氧化。此外，在 PS-MP 表面上发现了木质纤维素和硅酸盐作为异地附着物。考虑到 PS-MP 停留时间的变化，它们通过生物膜的形成吸引植物残留物和矿物质颗粒，并在河流环境中一起移动。鉴于 MP 的动态行为可能会受到其表面变化的极大影响，因此需要进一步研究来强调它们与有机物动力学的联系。
Microplastic (MP) surfaces are common sites for microbial colonization and promote biofilm formation in aquatic environments, resulting in changes to the surface properties of MPs and their interaction with pollutants. Although the diversity of microbial communities adhering to MPs has been well documented in aquatic environments, surface changes in MPs due to microbial colonization are still poorly understood. In this study, we aimed to evaluate the variations in the chemical structure and components of biofilms on the surface of polystyrene microplastics (PS-MPs) collected from the shore of the Tuul River in Mongolia, using micro-Fourier transform infrared (micro-FTIR) spectroscopy. We applied a spectral subtraction approach, and the differences in spectra between peroxide-treated and untreated PS-MP particles enabled us to obtain the structural features of biofilms that developed on the plastic surface. In addition, the surface photooxidation status of the sampled PSMPs was calculated from the subtracted spectra of peroxide-treated and pristine PS-MPs. Various functional groups of N-containing organic substances from bacterial and fungal communities were detected in the obtained biofilm spectra. Based on the spectral characteristics, biofilm spectra were classified into four groups by applying principal component analysis (PCA). A wide range of carbonyl indices (CIs: 0.00-1.40) was found in the subtracted spectra between peroxide-treated and pristine PS-MPs, revealing that different levels of surface oxidation progressed by physical influences such as solar radiation and freeze-thaw cycles. Furthermore, lignocellulose and silicate were found on the PS-MP surface as allochthonous attachments. Considering the variation in residence time of PS-MPs, they attract plant residues and mineral particles through the development of biofilms and travel together in the river environment. Given that the dynamic behavior of MPs can be greatly affected by changes in their surfaces, further studies are needed to emphasize their link to organic matter dynamics.