Nisin is a natural preservative produced by fermentation using the bacterium Lactococcus lactis. As a food additive, it has E number E234 in Europe.

Nisin,is a class of peptide compounds extracted from the fermentation product of Streptococcus lactis. It can effectively inhibit the growth and reproduction of gram-positive bacteria causing food spoilage, especially for heat-resistant Bacillus, Clostridium botulinum, Listeria monocytogenes and spores produced  by it, and can be used for meat products, dairy products, vegetable protein food, canned food preservation. Because nisin is a kind of polypeptide, it is easily decomposed by plant protease after entering the human body, it is a safe, non-toxic and efficient natural food preservative.