Compare the antibacterial effects of Nisin and chemical preservatives

As a biological preservative, nisin differs from chemical preservatives in terms of antibacterial spectrum, antibacterial efficacy, mechanism of action, and safety, as detailed below:

Antibacterial Spectrum: Nisin primarily exerts strong inhibitory effects on Gram-positive bacteria, such as Staphylococcus aureus and Listeria, and is generally ineffective against Gram-negative bacteria—though it can exert some effects after disrupting their outer membranes. Its inhibitory effect on molds and yeasts is poor. In contrast, common chemical preservatives like sodium benzoate and potassium sorbate have a relatively broader antibacterial spectrum: they not only inhibit some bacteria but also work well against molds and yeasts. For example, sodium benzoate can effectively inhibit the growth of many fungi and bacteria under acidic conditions.

Antibacterial Efficacy: Nisin has strong antibacterial efficacy, with higher stability and stronger activity in acidic environments. Studies have shown that in tests on inhibiting Bacillus in vinegar, Nisin outperforms chemical preservatives such as sodium benzoate and ethylparaben, producing larger inhibition zones and having a lower minimum inhibitory concentration.

Mechanism of Action: Nisin binds to lipid II on the cell membrane of Gram-positive bacteria, forming transmembrane channels that cause intracellular ions to flow out. It also blocks cell wall synthesis and induces oxidative stress and DNA damage, thereby inhibiting bacterial growth and reproduction. In contrast, chemical preservatives like sodium benzoate act by entering microbial cells and interfering with intracellular metabolic enzymes and energy metabolism—for instance, inhibiting key oxidases such as tartrate dehydrogenase and disrupting the tricarboxylic acid cycle to suppress microbial growth.

Safety: Nisin is a natural antimicrobial peptide produced by lactic acid bacteria with high safety. Approved for use by FAO/WHO, it is broken down into amino acids by proteases in the human digestive tract, leaving no residues or side effects. Chemical preservatives like sodium benzoate, while safe when used within specified doses, may cause allergic reactions such as asthma and rashes if ingested excessively; high-dose oral intake can even lead to severe adverse reactions like nausea and vomiting.