Nisin is a natural, toxicologically safe, antibacterial food preservative .

The suitability of nisin as a food preservative arises from the following characteristics: it is non-toxic, the producer strains of L. lactis are regarded as safe (food-grade); it is not used clinically; there is no apparent cross-resistance in bacteria that may effect antibiotic therapeutics; and it is quickly digested.

Nisin, a kind of polypeptide, is made by the controlled growth of lactococcus lactis , a bacterium which occurs naturally in milk. It is a natural food preservative with high efficiency to control Gram(+) and bacteria spoilage. But it is no effect to fungi such as mould and yeast. It is catabolized to amino acid in human body. So It is no harm or vice-effect to people.

Nisin exhibits antimicrobial activity towards a wide range of Gram positive bacteria, and is particularly effective against spores. It shows little or no activity against Gram negative bacteria, yeasts, and moulds.