Nisin is a bacteriocin produced by Lactococcus Lactis, subspecies lactis and cremoris strains.
Bacteriocins are proteic substances synthesized by some bacteria with the aim of hindering the growth of other microorganisms in the same environment. In particular, nisin is active against positive GRAMs (streptococci, bacilli and clostridia), while it has no activity against negative GRAMs.
Once taken, nisin is rapidly digested and inactivated by gastric and pancreatic proteases; consequently it does not negatively influence the human intestinal microflora. Its use in the industrial field mainly concerns the food sector, where it is added as a preservative (E234) in fruit juices, sour sauces (mayonnaise, ketchup), custard creams and dairy products (it is naturally found in dairy products). Nisin, in particular, performs its antimicrobial action at acid pH, while it is inactivated already in conditions of slight basicity.
