Export and modification of (poly)peptides in the lantibiotic way

The invention includes a method for harvesting a polypeptide produced by a host cell, wherein the polypeptide has not undergone intra-cellular post-translational modification, such as dehydration of a serine or a threonine, and/or thioether bridge formation. The invention also includes a method for producing thioether containing peptides and dehydroalanine/dehydrobutyrine-containing peptides, wherein extracellularly thioether rings may be formed