Regulatory effects of oxygen transfer on overexpression of recombinant benzaldehyde lyase production by Escherichia coli BL21 (DE3)

Effects of oxygen transfer (OT) on benzaldehyde lyase (BAL) production by recombinant E. coli BL21 (DE3) pLySs were investigated at an air‐inlet rate of QO/VR = 0.5 vvm and agitation rates of N = 250, 500, 625, and 750/min; and at constant dissolved oxygen (DO) concentrations of CDO = 0.04 and 0.08 mol/m3, on a glucose based defined medium. The highest cell concentration (CX = 3.0 kg/m3) and volumetric BAL activity (A = 1095 U/cm3) were obtained at CDO = 0.08 mol/m3. KLa increased with agitation rate and decreased with CX. The highest KLa (= 0.039 s(1) was obtained at QO/VR = 0.5 vvm and N = 750/min. Damköhler number increased with decrease in agitation rate and increase in CX, while the effectiveness factor was inversely proportional to CX. The specific growth rate and the yield coefficients decreased with cultivation time and higher values were obtained in higher agitation rates. Oxygen consumption and glucose consumption for maintenance were changed proportionally and inverse proportionally with the BAL production, respectively