Fig. 2
Schematic overview of the utilized bioreactor setups for L-phenylalanine production with recombinant Escherichia coli 4RP. The fed-batch cultivation in a stirred-tank bioreactor was characterized by consistent homogeneous conditions and the control of all process variables. In comparison, the two-compartment bioreactor setup combined a homogeneous zone in the stirred-tank bioreactor with a heterogeneous and uncontrolled zone within the coiled flow inverter with repetitive circulation of the cell suspension between both compartments applying a volumetric flow rate of 4.71 mL s−1, which corresponds to a mean hydraulic residence time of 102 s in the bypass