Lantibiotics synthesized by gram positive bacteria (Staphylococcus, Streptococcus, Bacillus, genera) are a special group of polycyclic polypeptides constituted of protein amino acids and unusual amino acids (i.e. lanthionine, beta-methyllantionine etc.) these last ones exhibiting interchain thioeter bridges and ring structures. Some lantibiotics are already used in medical therapy (nisin, gallidermin, epidermin) as well as for food preservation (nisin). Their special structures and synthesis have focused substantial scientific interest, the lantibiotics proving to be ideal experimental models not only for microbiology but also for biochemistry, molecular biology, gene technology and protein engineering in the purpose to get more insights in the fundamental aspects of the cell biology.