The preservative mechanism of nisin is primarily based on its unique antibacterial and bactericidal properties. Nisin exhibits strong inhibitory effects against most Gram-positive bacteria, especially the spores of Bacillus species. Its antibacterial mechanism is similar to that of cationic surfactants, primarily acting on the cell membrane. Specifically, nisin inhibits the biosynthesis of peptidoglycan in the cell wall, disrupting the synthesis of the cell membrane's phospholipid compounds. This disruption leads to changes in membrane permeability, causing the leakage of intracellular substances such as adenosine triphosphate (ATP), and even cell lysis. Through this process, it effectively inhibits the growth and reproduction of bacteria.

Under specific conditions, such as high temperature or acidic environments, nisin’s bactericidal effect becomes more pronounced. For example, in acidic conditions (around pH 2.5), its solubility is higher, and it demonstrates exceptional heat resistance. In such conditions, even spores that are difficult to eradicate can be effectively killed by nisin. Additionally, when used in combination with other preservatives (such as polylysine or potassium sorbate), its bactericidal effect is further enhanced.

As a natural food preservative, nisin is non-toxic and free from side effects. In the human body, Nisin is rapidly hydrolyzed into amino acids, which are essential nutrients, posing no harm to the body. Moreover, its usage level is very low; only a small amount is required to achieve effective preservation. Additionally, Nisin is environmentally friendly, causing no pollution.

Due to its excellent preservative properties and safety, nisin has been widely used in dairy products, meat products, canned goods, fish products, and alcoholic beverages. By inhibiting the growth and reproduction of harmful microorganisms, it significantly extends the shelf life of food while maintaining the color, aroma, flavor, and texture of the product.

The preservative mechanism of nisin is primarily achieved through its antibacterial and bactericidal action. This mechanism makes it an efficient, safe, and environmentally friendly natural food preservative, with wide application prospects in the food industry.