Nisin is an inhibitory polycyclic peptide with 34 amino acid residues used as a food preservative. It contains the uncommon amino acids lanthionine, methyllanthionine, dehydroalanine and dehydro-amino-butyric acid. These special amino acids are synthesized by posttranslational enzymatic modifications. In these reactions a ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids origin from serine and threonine. Peptides (from the Greek πεπτος, digestable), are the family of molecules formed from the linking, in a defined order, of various amino acids. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Lanthionine is a non proteinogenic amino acid found in peptides of microbial origin. ... Dehydroalanine (or (alpha)-(beta)-di-dehydroalanine) is an uncommon amino acid found in peptides of microbial origin (an unsaturated amino acid). ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = leaven) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Serine is one of the 20 most common natural amino acids on Earth. ... Threonine is one of the 20 most common natural amino acids on Earth. ...

Nisin is produced by fermentation using the bacterium Lactococcus lactis . Commercially it is obtained from natural substrates including milk and is not chemically synthesized. It is used in processed cheese production to extend shelf life by suppressing gram-positive spoilage and pathogenic bacteria. There are many other applications of this preservative in food and beverage production. Due to its highly selective spectrum of activity it is also employed as a selective agent in microbiological media for the isoloation of gram-negative bacteria, "yist" and moulds. Subtilin and Epidermin are related to Nisin. Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Species Lactococcus garvieae Lactococcus lactis Lactococcus piscium Lactococcus plantarum Lactococcus raffinolactis Lactococcus is the genus of bacteria formerly known as Streptococcus Group N and related species. ... Cheese is a solid food made from the curdled milk of various animals—most commonly cows but sometimes goats, sheep, reindeer, and water buffalo. ... Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. ...

Further reading

• K. Fukase et. al., Tetrahedron Lett. 1988, 29, 7, 795. (Total synthesis)
• G. W. Buchman et. al., J. Biol. Chem. 1988, 263, 31, 16260. (Biosynthesis)