Avoiding Acetate Accumulation in Escherichia coli Cultures Using Feedback Control of Glucose Feeding

In English An automated glucose feeding strategy that avoids acetate accumulationin cultivations of Escherichia coli is discussed. We havepreviously described how a probing technique makes it possible todetect and avoid overflow metabolism using a dissolved oxygen sensor.In this paper these ideas are extended with a safety net thatguarantees that aerobic conditions are maintained. The method isgenerally applicable as no strain specific information is needed andthe only sensor required is a standard dissolved oxygen probe. It alsogives the highest feed rate possible with respect to limitations fromoverflow metabolism and oxygen transfer, thus maximizing bioreactorproductivity.The strategy was implemented on three different laboratory-scale platformsand fed-batch cultivations under different operating conditions wereperformed with three recombinant strains, E. coli K-12 UL635,E. coli BL21(DE3), and E. coli K-12 UL634. In spite ofdisturbances from antifoam and induction of recombinant proteinproduction, the method reproducibly gave low concentrations of acetateand glucose.The ability to obtain favorable cultivation conditions independentlyof strain and operating conditions makes the presented strategy auseful tool, especially in situations where it is important to getgood results at the first attempt.