나이신 is a polycyclic antibacterial peptide composed of 34 amino acids, produced naturally during the fermentation of Lactococcus lactis. It is the only bacteriocin approved for use as a food preservative worldwide. 나이신 is particularly effective against gram-positive bacteria, including dangerous spore-forming species such as Clostridium botulinum, Listeria monocytogenes, and Bacillus cereus.
나이신 works by binding to lipid II, a key precursor in bacterial cell wall synthesis, and by forming pores in the cell membrane. This dual mechanism makes bacterial resistance development extremely rare. The peptide is heat-stable under acidic conditions and is degraded by digestive proteases in the human gut. 나이신 is approved by the WHO, FDA, and EFSA as a safe food additive and is listed as E234 in the European food additive system.