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Photochemical Behavior of Microbial Extracellular Polymeric Substances in the Aquatic Environment
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-09-15 , DOI: 10.1021/acs.est.1c02286 Shaofeng Zhou 1, 2 , Zhiyang Liao 1 , Beiping Zhang 1 , Rui Hou 1 , Yi Wang 1 , Shungui Zhou 3 , Yifeng Zhang 4 , Zhiyong Jason Ren 5 , Yong Yuan 1
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-09-15 , DOI: 10.1021/acs.est.1c02286 Shaofeng Zhou 1, 2 , Zhiyang Liao 1 , Beiping Zhang 1 , Rui Hou 1 , Yi Wang 1 , Shungui Zhou 3 , Yifeng Zhang 4 , Zhiyong Jason Ren 5 , Yong Yuan 1
Affiliation
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Microbially derived extracellular polymeric substances (EPSs) occupy a large portion of dissolved organic matter (DOM) in surface waters, but the understanding of the photochemical behaviors of EPS is still very limited. In this study, the photochemical characteristics of EPS from different microbial sources (Shewanella oneidensis, Escherichia coli, and sewage sludge flocs) were investigated in terms of the production of reactive species (RS), such as triplet intermediates (3EPS*), hydroxyl radicals (•OH), and singlet oxygen (1O2). The steady-state concentrations of •OH, 3EPS*, and 1O2 varied in the ranges of 2.55–8.73 × 10–17, 3.01–4.56 × 10–15, and 2.08–2.66 × 10–13 M, respectively, which were within the range reported for DOM from other sources. The steady-state concentrations of RS varied among different EPS isolates due to the diversity of their composition. A strong photochemical degradation of the protein-like components in EPS isolates was identified by excitation emission matrix fluorescence with parallel factor analysis, but relatively, humic-like components remained stable. Fourier-transform ion cyclotron resonance mass spectrometry further revealed that the aliphatic portion of EPS was resistant to irradiation, while other portions with lower H/C ratios and higher O/C ratios were more susceptible to photolysis, leading to the phototransformation of EPS to higher saturation and lower aromaticity. With the phototransformation of EPS, the RS derived from EPS could effectively promote the degradation of antibiotic tetracycline. The findings of this study provide new insights into the photoinduced self-evolution of EPS and the interrelated photochemical fate of contaminants in the aquatic environment.
中文翻译：
微生物胞外高分子物质在水生环境中的光化学行为
微生物来源的胞外聚合物（EPSs）占据了地表水中溶解有机物（DOM）的很大一部分，但对EPS光化学行为的理解仍然非常有限。在本研究中，研究了不同微生物来源（Shewanella oneidensis、大肠杆菌和污水污泥絮凝物）的 EPS 的光化学特性，研究了活性物质 (RS) 的产生，例如三重中间体 ( 3 EPS*)、羟基自由基 ( • OH) 和单线态氧 ( 1 O 2 )。• OH、3 EPS* 和1 O 2的稳态浓度在 2.55–8.73 × 10 –17、3.01–4.56 × 10 –15和 2.08–2.66 × 10 –13的范围内变化M 分别在其他来源的 DOM 报告的范围内。由于组成的多样性，不同 EPS 分离株的 RS 稳态浓度不同。通过具有平行因子分析的激发发射矩阵荧光鉴定出EPS分离物中蛋白质样成分的强烈光化学降解，但相对地，腐殖质样成分保持稳定。傅里叶变换离子回旋共振质谱进一步揭示EPS的脂肪族部分抗辐照，而其他H/C比和O/C比较低的部分更容易发生光解作用，导致EPS的光转化为更高的饱和度和较低的芳香度。随着EPS的光转化，EPS来源的RS可以有效促进抗生素四环素的降解。这项研究的结果为 EPS 的光诱导自我进化和水生环境中污染物的相关光化学归宿提供了新的见解。
更新日期：2021-11-16
中文翻译：
微生物胞外高分子物质在水生环境中的光化学行为
微生物来源的胞外聚合物（EPSs）占据了地表水中溶解有机物（DOM）的很大一部分，但对EPS光化学行为的理解仍然非常有限。在本研究中，研究了不同微生物来源（Shewanella oneidensis、大肠杆菌和污水污泥絮凝物）的 EPS 的光化学特性，研究了活性物质 (RS) 的产生，例如三重中间体 ( 3 EPS*)、羟基自由基 ( • OH) 和单线态氧 ( 1 O 2 )。• OH、3 EPS* 和1 O 2的稳态浓度在 2.55–8.73 × 10 –17、3.01–4.56 × 10 –15和 2.08–2.66 × 10 –13的范围内变化M 分别在其他来源的 DOM 报告的范围内。由于组成的多样性，不同 EPS 分离株的 RS 稳态浓度不同。通过具有平行因子分析的激发发射矩阵荧光鉴定出EPS分离物中蛋白质样成分的强烈光化学降解，但相对地，腐殖质样成分保持稳定。傅里叶变换离子回旋共振质谱进一步揭示EPS的脂肪族部分抗辐照，而其他H/C比和O/C比较低的部分更容易发生光解作用，导致EPS的光转化为更高的饱和度和较低的芳香度。随着EPS的光转化，EPS来源的RS可以有效促进抗生素四环素的降解。这项研究的结果为 EPS 的光诱导自我进化和水生环境中污染物的相关光化学归宿提供了新的见解。
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