Research About Interface Membrane Effect Between The Heavy Metal Coated Onto Pollution Dust And Human Common Bacteria

In this study, the high siliceous calcareous mineral fine particles and heavy metal pollutants?Pb???/Cd???/Cr???? in atmospheric particulate matter, were used as experimental materials to prepare heavy metal coated onto pollution dusts. Exp eriments were carried out to study the joint toxicit y effect and mechanism of the compound heavy metal pollution dust on the human common bacteria, Escherichia coli and Staphylococcus epi dermi dis. From membrane surface groups, oxidative damage and energy metabolism three aspects to explore the interface membrane effect between the heavy metal coated onto pollution dust and human common bacteria.After exposure to the heavy metal ions?Pb???, Cd??? or Cr????, position of E.coli membrane surface dihydrogen phospha te ester groups shifted, protein amide I band beta sheets/alpha helices ratio decreased obviousl y, suggesting that the secondary structure of bacterial surface proteins were changed. The succinodehydrogenase, Na+–K+–ATPase and Ca²⁺–Mg²⁺–ATPase activity decreased first then increased with the heavy metal ions content increas ing. And Pb??? and Cd??? inhibited respiratory chain dehydrogenase activit y, resulting in accumulation of semiubiquinones at the Q0 site, which in turn stimulated ROS production, glutat hione depletion with a concomitant incr ease in malondialdehyde levels, demonstrated that heavy metal induce oxidative stress leading to cyt otoxicit y in E.col i. Revealing that the heavy metal ions in the appro priate concentration range, promoted the growth of bacteria and cell aerobic respiration, but excessive concentrations of heavy metal ions inhibited bacteria energy metabolism enz yme activit y, leading to bacterial energy metabolic disorders, enhanced bacterial oxidative stress level, and produced toxic to bacteria.The influence of heavy metal coated onto high silicon dust on E.coli surface groups were focused on membrane surface dihydrogen phosphate ester groups, pol ysaccharide molecules and protein secondary structure. The membrane bound enz yme?SDH, ATPase? activit y ma y be a compen-satory increase, decomposing more ATP to bacterial resistance to oxidative stress. Effects on intermembrane antioxidant system shown that bacteria intracellular ROS increased, the glutathione levels dropped, lipid per-oxidation level rose, and caused oxidative damage. Revealing that the heavy metal coated onto high silicon dust affect ed the bacterial membrane surface functional groups, energy metabolic enz ymes and intracellular oxidative stress level.After exposure to the heavy metal coated onto calcareous dust in PBS buffer solution, E.coli cell vitalit y reduced, membrane surface functional groups?pol ysacchari de, protein molecules and phosphoric acid ester group? were damaged, and oxidative stress levels increased. When E.coli were exposed to the heavy metal coated onto calcareous dust in 0.9% Na Cl solution, a significant increase in cell vitalit y was observed, which was mainl y caused by the dissolution Ca²⁺ of high calcium dust. The joint toxicit y of Ca²⁺ and heavy meta l ions on E.coli shown that, when E.coli were exposed to Ca²⁺ in the presence of low concentration of Pb??? and Cd???, Ca²⁺ significantl y alleviated the toxicit y of heavy metal ions, when the concentrations of Pb??? and Cd??? increased, Ca²⁺ increased the toxicit y of high concentration s of Pb??? and Cd???, synergisticall y affecting bacteria normal energy metabo lism and oxidative stress level.There was a significant interaction between the high silica dust, high calcium powder and Pb???/Cd???/Cr???, weakened the joint toxicit y effect of high calcium silicon dust and heavy metal ions on E. coli, to a certain extent. High concentration of heavy metal coated onto high silicon calcium dust showed a certain synergistic toxic effects on bacteria, but the toxicit y was still less than the addition toxicit y of heavy metal ion with high calcium silicon dust. Research showed that the interface membrane effect between the heavy metal coated onto pollution dust and human common bacteria showed a larger difference, due to the difference of bacterial membrane structure, function medium, mineral particle size and heavy metal composite patterns.In general, in the experimental study dose range, the characteristics toxic effects of the high siliceous calcareous mineral fine part icles on E.col i cells showed the poison excited effect, namel y, when low dose of heavy metals added, the toxic effects presented the excitement effect, reflecting in the bacterial intracellular antioxidant enz ymes and energy metabolism enz yme activit y incr eased. But when high dose of heavy metals added, the toxic effects presented the inhibiting effect, reflecting in the bacterial intracellular antioxidant enz ym es and energy metabolism enz yme activit y showed a downward trend. The toxic differences between h igh siliceous dust and high calcareous dust on E.coli were mainl y caused by the physical and chemical characteristics?surface potential, dissolving proper-ties, etc.? of high calcium silicon dust itself.