15 March 2006 - The Commission has asked the European Food Safety Authority to issue an opinion on the safety in use of nisin. In addition, EFSA was asked to address the issue of antimicrobial resistance and the use of nisin.
Nisin (E234) is authorised for food preservation in the European Union by Directive 95/2/EC on food additives other than colours and sweeteners. Nisin is permitted in ripened cheese and processed cheese, certain puddings, clotted cream and mascarpone. Nisin is a group of closely related polypeptides composed of 34 amino acids, and is produced by certain strains of the bacterium Lactococcus (Streptococcus) lactis ssp. lactis. It has a narrow spectrum of activity affecting primarily vegetative cells and spores of Gram-positive bacteria. Bacteria susceptible to nisin include other lactic acid bacteria, Bacillus, Clostridium, Listeria, and Streptococcus genera. In the absence of other preservation methods, nisin does not inhibit Gram-negative bacteria, yeasts, or moulds. Consequently nisin is often used in combination with other synergistic preservation methods (known as hurdle technology) such as low pH and high salt concentrations.
Nisin is a bacteriocin. These are proteins or polypeptides produced by bacteria that kill or inhibit the growth of other bacteria. Bacteriocins differ from antibiotics according to their synthesis, mode of action, toxicity and resistance mechanisms. Many lactic acid bacteria, such as L. lactis, are found in various fermented dairy and meat products and produce a diverse range of bacteriocins. Nisin may be present in food due to the presence of the lactic acid bacteria used as starter cultures, or may be added directly. Ingested nisin is inactivated by trypsin and pancreatin and will have no effect on the gut microflora. The Panel did not find any data, that would warrant any change of the Acceptable Daily Intake (ADI) of 0.13 mg nisin/kg bw previously established by Scientific Committee on Food (SCF). The Panel furthermore noted that there has been exposure to nisin for many centuries and concluded that nisin can be safely used. Nisin has a double mode of antimicrobial action; binding to lipid II and subsequent inhibition of cell wall synthesis as well as forming pores in the cytoplasmic membrane. Nisin is only used as a food preservative and has currently no therapeutic use. Sporadic nisin resistant mutants do not show any cross-resistance to therapeutic antibiotics. The Panel considered that this is probably due to the differences in the antimicrobial mode of action between therapeutic antibiotics and nisin and that development of antibiotic resistance is not of concern in relation to use of nisin in food.