Expression system for the antibiotic-free production of polypeptides

摘要

The present invention relates to a microbial expression system for the production of polypeptides based on the use of extrachromosomal DNA, whereby no antibiotic marker genes for the selection of the host cell but DNA sequences that encode glycerine-3-phosphate dehydrogenase are used, and, thus, the production of the desired polypeptide, e.g., xylanase, does not need the addition of antibiotics. The expression system is free from antibiotic-resistance genes. The invention further relates to a DNA sequence that encodes a polypeptide with glycerine-3-phosphate dehydrogenase activity as well as a polypeptide with glycerine-3-phosphate dehydrogenase activity.