Studies On Inhibition Effect Of Sodium Humate On E.coli And Its Mechanism

Ovine Colibacillosis is one of the diseases occurring frequently in north of China during the winter and spring, which has the characteristics of rapid incidence and short time of death. And it is a communicable disease which should be prevented seriously in livestock production. Sodium humate as a feed additive has been widely used in animal productions in order to improve animal performance and prevent diseases. This study mainly studied the inhibiting effect and its mechanism of sodium humate on 4 strains of poisonous Escherichia coli, which were separated from the intestinal tracts of lamb. The results were following:1. E.coli treated by sodium humate has been detected with PI fluorescence by using the fluorescence spectrophotometer and flow cytometry. Results show that even though the tolerance ability for different strains of E.coli to humic acid sodium was different, but with the increasing concentration of sodium humic (1%-5%), the cell relatively permeability of E.coli rose and the rate of injured cell grew. When the concentration of sodium humic acid was 5%, the mortality rate of E.coli reached about 40%. Thus, sodium humic can inhibit E.coli and the inhibitory effect increased with the concentration of sodium humate.2. Effect of sodium humate on fatty acids composition and content of E. coli cell membrane has been detected by using gas chromatograph, in order to explore the inhibition mechanism of sodium humate on E. coli from the level of fatty acids metabolism of cell membrane. Results show that with the increasing concentration of sodium humic, unsaturated degree of fatty acids in E. coli cell membrane decreased and cell membrane fluidity increased, which could cause the change of E. coli cell membrane structure, cell lipid metabolic abnormalities.Therefore, E. coli can be inhibited by sodium humic.3. Effect of sodium humate on the changes of fluorescence spectra of E.coli bacteria protein has been detected by using the endogenous fluorescence spectrophotometry, which can explore the inhibition mechanism of sodium humate on E. coli from the aspects of cell membrane protein structure. Results showed that the E.coli cell membrane protein fluorescence quenching phenomenon was much more obvious with the increasing concentration of sodium humate. It caused the change of conformation of membrane proteins and transport abnormalities in E. coli cell. Thus, the inhibition mechanism of sodium humate on E. coli can be achieved.4. Effects of sodium humate on modality of E. coli was observed by using transmission electron in order to verify the inhibition of sodium humate on E. coli. Result indicates the plasmolysis of E. coli cells was induced with the concentration increasing of sodium humic and the cavity of E. coli was shaped due to the leakage of cell contents. Furthermore, it can cause disorders of material synthesis metabolic which intuitively reflect the inhibition of sodium humate on E. coli.