In the field of food preservation and biological freshness maintenance, nisin and lysozyme are two widely used natural biological preservatives. Though both act as safe and highly effective "green guardians", they differ significantly in origin, mechanism of action, and application scenarios. At the same time, they form a clever synergy that builds a double line of defense for food safety.

Fundamentally, their origins are completely distinct. Nisin is a peptide compound produced by the fermentation of Streptococcus lactis—a metabolic product synthesized by the bacterium itself. Its production process is similar to yogurt fermentation, and its natural properties have earned it the "GRAS" (Generally Recognized as Safe) certification from the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). Lysozyme, by contrast, is an alkaline globulin widely present in egg whites, human saliva, and tears. Most commercially used lysozyme is extracted from egg whites, making it a typical representative of animal-sourced natural antibacterial ingredients.

Differences in their mechanisms of action result in a contrast between "targeted attack" and "broad-spectrum defense". Nisin acts with extreme specificity: it can accurately identify the cell membranes of Gram-positive bacteria (such as Bacillus subtilis, which causes food spoilage, and Staphylococcus aureus, which triggers food poisoning). By damaging the integrity of these cell membranes, it causes the leakage of bacterial contents and subsequent bacterial death. However, it is essentially ineffective against Gram-negative bacteria. Lysozyme, on the other hand, functions more like a "broad-spectrum disassembler": it specifically destroys the peptidoglycan structure in bacterial cell walls. Any bacterium—whether Gram-positive or some Gram-negative strains (e.g., Escherichia coli)—with peptidoglycan in its cell wall will be "dissolved" by lysozyme. Notably, it also exerts a certain inhibitory effect on fungi and yeasts.

These differences precisely create their complementary advantages. In food preservation applications, using nisin alone struggles to address Gram-negative bacterial contamination, a gap that lysozyme can fill. Conversely, lysozyme has a weak inhibitory effect on some highly resistant Gram-positive bacteria, which nisin can accurately eliminate. For example, in the processing of low-temperature meat products, the combined use of both preservatives allows nisin to inhibit heat-resistant spore-forming bacteria while lysozyme controls pathogenic bacteria such as E. coli. This combination boosts preservation efficacy by over 30% compared to using either alone, while also reducing the amount of chemical preservatives required—aligning perfectly with consumers’ demand for "natural and healthy" food.