The remarkable preservative efficacy of nisin stems from its unique and sophisticated antimicrobial mechanism. Its antibacterial action is primarily achieved through interference with the normal function of bacterial cell membranes — nisin molecules adsorb onto the surface of Gram-positive bacterial cell membranes, forming pores that alter membrane permeability, leading to nutrient loss and membrane potential depolarization, ultimately resulting in the death of pathogenic and spoilage bacteria.

In terms of antimicrobial spectrum, nisin effectively inhibits a wide range of Gram-positive bacteria responsible for food spoilage, including Lactobacillus, Leuconostoc, Pediococcus, Staphylococcus, and Listeria. Notably, it exhibits potent inhibitory effects against spore-forming bacteria such as Bacillus, Clostridium, and Clostridium botulinum. These spore-forming bacteria typically possess strong heat resistance, making them difficult to eliminate completely through conventional thermal treatment. For instance, even after ultra-high temperature instantaneous sterilization at 135°C for 2 seconds, approximately 10% of spore-forming bacteria may survive. The addition of 0.03–0.05 g/kg of nisin can effectively inhibit the germination and proliferation of Bacillus and Clostridium spores.

In terms of physicochemical properties, nisin demonstrates excellent solubility and stability. Its solubility varies with pH: 12% at pH 2.5, decreasing to 4% at pH 5.0, and is essentially insoluble under neutral and alkaline conditions. Thermal stability is also closely related to pH: in dilute hydrochloric acid at pH 3, nisin retains 100% activity after autoclaving at 121°C for 15 minutes; in skim milk at pH 6.5, it loses only 15% activity after pasteurization at 85°C for 15 minutes. This excellent acid and heat resistance enables nisin to adapt to a wide range of food processing conditions.

References

(1) Lv S X et al. Study on antibacterial function and mechanism of Nisin[J]. China Brewing, 2008(5): 87-91.

(2) Han D Q, Ding H B. Molecular structure, antimicrobial activity and genetic engineering of Nisin[J]. Biotechnology Bulletin, 2005(5): 35-38.

(3) Xia Y T, Zhu K M. Characteristics of Nisin and its application in meat products. Department of Food Science and Engineering, Nanchang University.

(4) ChemicalBook. Nisin 1414-45-5

(5) Food Encyclopedia. Research and application of microbial preservative Nisin