What are the active ingredients of nisin

New weapon against unruly germs

The microbiologists do not call their discovery an antibiotic, but a lantibiotic. "The term is derived from lantionine-containing antibiotic peptides," says Hans Georg Sahl from Institute for Medical Microbiology at the University of Bonn clear. The highlight: The small protein molecules have an extraordinary component: the amino acid lantionine.

Together with colleagues from the Netherlands, Sahl examined a well-known substance from this group of active ingredients, the so-called nisin, which itself comes from the widespread bacterial species of the lactococci. "These unicellular organisms, to which we owe our cheese, naturally produce nisin." The lantibiotic nisin kills other bacteria or at least inhibits their growth in cheese and other foods - a natural preservative, so to speak. The conclusion to its use was therefore obvious: "Because the nisin concentration that the lactococci leave behind cannot always be precisely estimated, the molecule was added artificially," reports the scientist from the University of Bonn.

The cheese ingredient proved to be unsuitable as a drug: the substance did not distribute itself sufficiently in the body. In addition, the immune system tries to neutralize the intruder itself. Nonetheless, nisin has excellent properties, because various bacteria were unable to protect themselves against the protein containing lantion. On the one hand, nisin prevents - like many antibiotics - the build-up of the protective cell wall of certain bacteria. In the case of existing bacteria, it also tears holes in the membrane, and the germs simply run out.

Both types of action work via special receptors on the target organisms: nisin, as it were, cracks the locks of the dangerous cells - there is no protection against this for the germs. The researchers therefore believe that they have found a drug against which pathogens cannot become resistant. Because nisin itself is not suitable as a medicine, pharmacologists have spent years developing new active ingredients that use the nisin trick. Until then, Hans Georg Sahl recommends the careful use of conventional antibiotics in order to keep the development of resistance as low as possible. Then the vital drugs could be used well into the next millennium, until the lantibiotics can take their place.