Nisin is a natural antimicrobial peptide that is produced by certain strains of the bacterium Lactococcus lactis. It is commonly used as a food preservative to inhibit the growth of spoilage microorganisms and pathogenic bacteria in various food products. Nisin is a polypeptide, meaning it is a peptide made up of a chain of amino acids. It consists of 34 amino acid residues and has a molecular weight of approximately 3,500 Da (daltons). Nisin contains several unusual amino acids, including lanthionine and β-methyl-lanthionine, which are formed during its biosynthesis. Nisin is a naturally occurring antimicrobial compound that is produced by certain strains of Lactococcus lactis, a lactic acid bacteria commonly used in the fermentation of dairy products. Nisin has potent antimicrobial properties, particularly against gram-positive bacteria. It is effective against a broad spectrum of bacteria, including species of Listeria, Clostridium, Bacillus, and Staphylococcus. Nisin works by disrupting the cell membranes of bacteria, leading to cell death. It forms pores in the bacterial cell membranes, causing ions to leak out and disrupting essential cellular functions. Nisin is commonly used in the food and beverage industry as a natural preservative. It helps extend the shelf life of a variety of food products by preventing the growth of spoilage microorganisms and pathogenic bacteria. Nisin is generally recognized as safe (GRAS) by regulatory authorities in many countries when used at recommended levels in food products. It has a long history of safe use and is approved for use in a wide range of food applications. The specific dosage of nisin in food products can vary depending on the product and its intended use. Regulatory agencies provide guidelines for the safe use of nisin in food. Nisin is often used in combination with other food preservatives or preservation methods to enhance its effectiveness. It is sometimes used in conjunction with other antimicrobial compounds to provide a broader spectrum of activity. Nisin is an important tool in food preservation, as it can help improve food safety and extend the shelf life of a variety of perishable products. It is valued for its effectiveness against a range of bacteria and its long history of safe use in the food industry.