SELEKTIONSSYSTEM INDEHOLDENDE NON-ANTIBIOTISK RESISTENSSELEKTIONSMARKØR

摘要

A selection system free of antibiotic resistance genes, which is based on the use of an araD gene as a selection marker carried on a vector which is inserted in a bacterial strain deficient of the araD gene. The araD gene from E. coli encodes the L-ribulose-5-phosphate-4-epimerase. A method of selecting the cells transformed with a plasmid, which contains the araD gene. The non-antibiotic selection marker makes the system suitable for producing therapeutics. The araD gene is not essential for growth of the host but manipulation of it affects the growth under certain selective conditions. Deletion of araD leads to accumulation of substance which is toxic to the host but not to humans. The araD gene is relatively small and therefore a small plasmid may be constructed, which requires less energy for replication, and leads to increased growth rate and yield.