Antimicrobial stability of lysozyme under different pH,temperature and metal ions

In this research, Staphylococcus aureus and Escherichia coli O157:H7 were selected as the tested bacteria. To evaluate the antibacterial stability of lysozyme (LYS)at different pH, temperatures and metal ion, the inhibitory rate of LYS against Staphylococcus aureus and Escherichia coli O157:H7 was detected. The results showed that the inhibitory effect of LYS on Staphylococcus aureus was stronger than that of Escherichia coli O157:H7, and the minimum inhibitory concentration was 1.3×10^-3 g/mL and 2.6×10^-3 g/mL, respectively. LYS had a good bacteriostatic effect on Staphylococcus aureus and Escherichia coli O157:H7 under acidic conditions, especially at pH4~6.After thermal treatments from 4~121℃, the antibacterial activity of LYS was not influenced. Different metal ions had a distinguished effects on the antibacterial activity of LYS. Zn²⁺ and Mn²⁺ had a strong synergistic effect with LYS, while Mg²⁺ and Ca²⁺had some antagonistic effect, which could reduce the antibacterial effect of LYS.