| This study observed the germicidal effects of silver combined disinfectant (SCD), and the efficiency was adversely affected by temperature, pH value, and organisms,among which there existed interaction. The silver ion is the main disinfecting component in this combined disinfectant. Silver ion has been used as a disinfectant for many years, despite the lack of research on its mechanisms, especially the lack of research on the mechanisms of the molecular level. The study was conducted to examine the effects of SCD on the ultrastructure of Staphylococcus aureus in order to elucidate the bactericidal mechanism of SCD.Meanwhile the leakage of proteins were detected.And by the agar gel electrophoresis studies about destructive effect on DNA double-strends of Staphylococcus aureus were conducted. The results showed that silver combined disinfectant could kill the Escherchia coli, staphylococcus aureus and candida abbicans efficiently. But, the significant effect was not seen on the spores of Bacillus var. Its disinfectant efficacy was affected by temperature, pH value and organisms. The efficiency of sterilization decreased with the increasing pH value, and organisms content and the rising temperature. The bactericidal mechanisms of disinfectant were based on destroying the cell wall and membrane, making it swelling, loosing , fracturing. The permeability thus increased that leaded to the leakage of proteins and other materials in the cell and ultimately the death of cell. The ultrastructure was observed by transmission electron microscope (TEM) also. When treated with 50mg/L Ag+, there was no apparent destruction in Stahylococcus aureus body andits inner construction. When treated with 100mg/L,250mg/L or 500mg/L Ag+, the cell wall was loosely, uneven, and the widened space between cell wall and membrane was seen clearly. With prolonging the contact time, the leakage of proteins increased, this further proved that the silver ions could damage the cellular permeability barrier. The results of electrophoresis indicated that silver ions might also act on the bacteria DNA, and produce DNA strands broken to result in cell death. Further research should be done to evaluate the advanced effects of silver ions on the DNA in the bacteria, and its ability in killing bacteria. |
