Nisin is an antibacterial peptide produced by Lactococcus lactis. The molecule has a polycyclic structure and contains 34 amino acids. It serves as a preservative in selected foods, inhibiting Gram-positive spoilage bacteria. Applications include canned fruit, canned vegetables and cheese. The material is a white to pale-yellow powder, with food grade recorded in the catalogue. Food use as E 234 is subject to the applicable food-additive specification and permitted-use conditions. Use in biocidal products depends on the applicable product authorisation.