Modeling Analysis of Oxygen Transfer Efficiency in Rest Cell Catalysis for Extra High-Titer Xylonic Acid Bioproduction

Abstract

The conflict arising from high-titer products and substantial oxygen requirements in aerobic bioconversion results in high-viscosity and oxygen transfer bottlenecks in dynamically changing biosystems. Currently, in the bioproduction of xylonic acid (XA), strategies to address the oxygen transfer bottleneck predominantly focus on macro-level modifications of the bioreactor. In this study, aiming at the high-viscosity biosystem, the optimal rotational speed equation was established at the fluid level by quantitatively investigating the variations and limitations of fluid rheological characteristics, gas holdup, cell respiration rate, and volume transfer coefficient of broth under different concentrations and rotational speeds. Based on the cell respiration rate under the optimal rotation speed, the theoretical production performance was calculated, and 679.3 g/L XA was achieved with the productivity of 14.2 g/L/h by batch feeding mode. Verified using actual production under the same conditions as a control, 649.3 g/L XA was finally accumulated with a productivity of 13.5 g/L/h, which was equivalent to 95.8% of the theoretical production. The intensification strategy for oxygen transfer provided insightful ideas to overcome the stubborn obstacles of obligate aerobic catalysis. Moreover, the study offered technical assistance and application potential for the production of high-titer XA from high-viscosity sugar-rich lignocellulosic hydrolysate.