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

摘要

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 Q_O/V_R = 0.5 vvm and agitation rates of N = 250, 500, 625, and 750/min; and at constant dissolved oxygen (DO) concentrations of C_(DO) = 0.04 and 0.08 mol/m~3, on a glucose based defined medium. The highest cell concentration (C_X = 3.0 kg/m~3) and volumetric BAL activity (A = 1095 U/cm~3) were obtained at C_(DO) = 0.08 mol/m~3. K_La increased with agitation rate and decreased with C_x. The highest K_La (= 0.039 s~(-1)) was obtained at Q_O/V_R = 0.5 vvm and N = 750/min. Damkohler number increased with decrease in agitation rate and increase in C_X, while the effectiveness factor was inversely proportional to C_X. 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.