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以大肠杆菌为研究对象,通过检测尺寸为20nm的零价纳米铁暴露下大肠杆菌形貌、生长曲线和细胞内酶活性的变化,研究了零价纳米铁对大肠杆菌的毒性效应,并探讨了其可能的毒性机制。用透射电镜(TEM)观察零价纳米铁与大肠杆菌(JM109)接触后细胞的形态变化;用0、112、560和1120mg·L-1的零价纳米铁染毒大肠杆菌细胞,测定大肠杆菌的生长曲线变化;并测定零价纳米铁染毒24h后细胞培养液上清中乳酸脱氢酶(LDH)活性、细胞内超氧化物歧化酶(SOD)活性、丙二醛(MDA)的含量,同时观察加入抗氧化剂N-乙酰半胱氨酸(NAC)后细胞的生长变化。结果表明,零价纳米铁能够破坏细胞完整性,造成细胞损伤;抑制大肠杆菌的细胞生长,缩短大肠杆菌的对数期,延长稳定期;零价纳米铁浓度越高,大肠杆菌的稳定期越长。零价纳米铁还可导致细胞培养上清液中LDH活性显著升高,细胞内SOD活性显著下降,MDA含量显著升高,且MDA含量变化与零价纳米铁浓度存在剂量-效应关系。加入抗氧化剂NAC后,加NAC的实验组细胞数大于没加NAC的实验组。以上结果表明零价纳米铁的毒性机制为氧化损伤。
Escherichia coli as the research object, by detecting the size of 20nm zero-valent nano-iron exposed Escherichia coli morphology, growth curves and changes in intracellular enzyme activity of zero-valent nano-iron on E. coli toxicity and discussed Its possible toxicity mechanism. Transmission electron microscopy (TEM) was used to observe the morphological changes of cells after the contact of zero-valent nano-iron with E.coli JM109. E.coli cells were treated with 0, 112, 560 and 1120 mg · L-1 zero- (LDH) activity, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the supernatant of the cell culture medium after 24 hours of zero-valent nano- , While observing the growth of cells after addition of antioxidant N-acetylcysteine (NAC). The results showed that zero-valent nano-iron could destroy cell integrity and cause cell damage, inhibit cell growth of Escherichia coli, shorten the logarithmic phase of Escherichia coli and prolong the stable period. The higher the concentration of zero-valent nano-iron, the more stable the Escherichia coli long. Zero-valent nano-iron also led to a significant increase in LDH activity in cell culture supernatant, a significant decrease in intracellular SOD activity and a significant increase in MDA content, and a dose-effect relationship between the change of MDA content and the zero-valent nano-iron concentration. After adding antioxidant NAC, the number of cells in the experimental group with NAC was larger than that in the experimental group without NAC. The above results indicate that the toxicity mechanism of zero-valent nano-iron is oxidative damage.