铜离子对引起仔猪腹泻的大肠杆菌K_(88)杀菌机理的研究

Studies on antibacterial mechanism of cupric ions in Escherichia coli K_(88)

采用K+电极对大肠杆菌K88细胞内的K+释放进行测定;采用氧电极法对其呼吸耗氧量进行测定;采用透射电子显微镜观察细胞壁结构的完整性,从而探讨硫酸铜(CuSO4)的杀菌机理。研究表明:Cu2+在微摩尔水平时就能有效抑制微生物的呼吸代谢途径。比较了典型抑制剂对硫酸铜的叠加率,得出硫酸铜主要抑制呼吸代谢的HMP途径。而且Cu2+还可诱导K+从细胞内释放出来,使细菌死亡。但它是一个可逆的过程,营养基质和EDTA可阻止细胞内K+的释放。在透射电镜下观察细菌细胞壁的完整性被破坏。因此,硫酸铜在肠道中可有效杀死引起腹泻的病原菌大肠杆菌K88。

The release of K^+ from the Escherichia coli K_(88) cells was assayed using a K+ specific electrode. Oxygen consumption was measured polarographically by using of SP-II type oxygen electrode. The results showed Cu^(2+) was bactericidal to the enteropathogenic bacterium E. coli K_(88) in the micromolar level and inhibited oxygen consumption efficiently. Copper sulfate (Cu^(2+)) mainly inhibited HMP route of bacteria. Moreover, cupric ions also induced leakage of K^+ in the E. coli K_(88) and caused cell death. But this phenomenon was reversible. If added to EDTA chelating agents or plating on nutrient agar was able to restore the respiration and to stop the release of K^+ in Cu^(2+)-treated cells. It was obviously observed by transmissional electronic microscope(TEM)that cell walls of bacteria were destroyed. Therefore,copper sulfate(Cu^(2+)) can kill enteropathogens efficiently which caused diarrhea of weanling pigs and stimulate their growth.