The synergistic antibacterial effect of Nisin and chelating agents

Nisin is a natural biological preservative with good antibacterial effects, especially a strong inhibitory effect on Gram-positive bacteria. Chelating agents are a class of compounds that can form stable complexes with metal ions. When they act synergistically with nisin, they often produce better antibacterial effects, which are specifically manifested as follows:

Enhancing cell membrane permeability: Chelating agents can bind to metal ions on the surface of the bacterial cell membrane, changing the structure and function of the cell membrane and increasing its permeability. This makes it easier for nisin to enter the bacterial cells, enabling it to better exert its antibacterial effect. For example, EDTA (ethylenediaminetetraacetic acid), a commonly used chelating agent, can chelate calcium and magnesium ions on the cell membrane, disrupting the integrity of the cell membrane and allowing nisin to more easily penetrate the cell membrane and act on the intracellular targets.

Improving the stability of Nisin: Metal ions such as iron ions and copper ions may catalyze the oxidation reaction of nisin, leading to a decrease in its activity. Chelating agents can chelate these metal ions, reducing their oxidative effect on nisin and thus improving the stability of nisin in the system, enabling its antibacterial activity to be better maintained. For instance, in some food systems, the addition of chelating agents can prevent nisin from being inactivated due to the presence of metal ions and prolong its antibacterial duration.

Expanding the antibacterial spectrum: Nisin has a relatively weak inhibitory effect on Gram-negative bacteria because the outer membrane structure of Gram-negative bacteria hinders its binding to intracellular targets. Chelating agents can remove divalent metal ions such as calcium and magnesium ions from the outer membrane of Gram-negative bacteria, making the outer membrane structure loose and increasing its permeability, thus allowing nisin to enter the cells and exert its effect, and further expanding the antibacterial spectrum of nisin, so that Gram-negative bacteria that were originally insensitive to it can also be inhibited. For example, when nisin is used in combination with EDTA, it can effectively inhibit the growth of Gram-negative bacteria such as Escherichia coli and Salmonella.

The synergistic antibacterial effect of nisin and chelating agents can play a positive role in enhancing cell membrane permeability, improving the stability of nisin, and expanding the antibacterial spectrum, thereby more effectively inhibiting bacterial growth, prolonging the shelf life of products such as food, and having broad application prospects in multiple fields such as food, cosmetics, and pharmaceuticals.