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以大气颗粒物中的高硅质矿物细颗粒——石英粉尘和重金属离子附载污染物Pb(Ⅱ)为实验材料,人工制备载铅石英粉尘。以1.6g·L~(-1)的载铅(Ⅱ)石英粉尘及不同浓度的PbCl2染毒大肠杆菌细胞,观察染毒2h后对机体的联合氧化损伤效应,并探讨其对大肠杆菌表面基团及蛋白酰胺I带二级结构的影响。结果表明,与Pb(Ⅱ)、载铅石英粉尘作用后,大肠杆菌细胞活力降低,胞内活性氧(ROS)及丙二醛(MDA)产生增多、谷胱甘肽(GSH)含量下降,引起细菌氧化应激水平的提高;皮尔逊(Pearson)相关性分析显示载铅石英粉尘的细菌毒性与粉尘中Pb(Ⅱ)可交换态含量成正相关,载带高浓度Pb(Ⅱ)的石英粉尘组胞内ROS/MDA水平与其单纯石英粉尘组和Pb(Ⅱ)组比较显著增加(p<0.05);重金属Pb(Ⅱ)、载铅石英粉尘对大肠杆菌菌体表面基团的影响主要集中于磷酸二酯基团和表面多糖分子,采用二阶导、去卷积和谱线拟合技术对酰胺Ⅰ带特征峰(1 600~1 700cm~(-1))进行分峰拟合后发现,与Pb(Ⅱ)、载铅石英粉尘(Q-Pb-0,Q-Pb-3)作用后,β-sheets/α-helices的比值由对照组的1.41分别降低到1.33,1.27和1.22,表明细菌表面蛋白质结构发生了变化,从而可能影响了细菌的生理活动。研究表明自由基所产生的氧化损伤可能是载Pb(Ⅱ)石英粉尘的一种重要毒性作用机制,载带Pb(Ⅱ)的复合石英粉尘在致大肠杆菌机体氧化损伤效应方面二者存在一定的协同作用。
A Pb-bearing quartz dust was artificially prepared by using Pb (Ⅱ) as a contaminant loaded with high siliceous mineral particles - quartz dust and heavy metal ions in atmospheric particles. The cells were exposed to 1.6 g · L -1 lead (Ⅱ) quartz dust and different concentrations of PbCl2 to observe the effect of combined oxidative damage on the body after 2 hours of exposure and to explore the effect on the surface of E. coli The influence of the secondary structure of the amide group and the amide I. The results showed that after Pb (Ⅱ) and lead-bearing quartz dust were added, the viability of E.coli cells was decreased, the production of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) increased and the content of glutathione (GSH) Bacterial oxidative stress increased; Pearson correlation analysis showed that the bacterial toxicity of lead-loaded quartz dust was positively correlated with Pb (Ⅱ) exchangeable content in dust, and quartz dust group with high Pb (Ⅱ) concentration The intracellular levels of ROS / MDA were significantly increased compared with those of pure silica dust group and Pb (Ⅱ) group (p <0.05). The effects of heavy metal Pb (Ⅱ) and lead-bearing quartz dust on the surface groups of Escherichia coli mainly concentrated in the presence of phosphoric acid Diester groups and surface polysaccharides, the second-derivative, deconvolution and spectral fitting techniques were used to fit the peak of the amide Ⅰ band (1 600 ~ 1 700cm -1) The ratios of β-sheets / α-helices decreased from 1.41 in the control group to 1.33, 1.27 and 1.22 respectively after Pb (Ⅱ) and Pb-Pb-0, Q-Pb- Surface protein structure has changed, which may affect the bacterial physiological activity. Studies have shown that the oxidative damage caused by free radicals may be an important toxic mechanism of Pb (II) -containing quartz dust. There is a certain degree of oxidative damage effect of Pb (II) -containing composite quartz dust on Escherichia coli Synergy.