서강대학교

초록 (요약문)

Formate dehydrogenase (FDH), with EC number of 1. 17. 1. 9, is an enzyme that promotes a reversible reaction converting formate to CO2. FDH plays a crucial role in the biological CO gas conversion process, where formic acid is produced by using a series of enzymes including FDH. In this study, fed-batch cultivations for mass production of FDH were performed using recombinant methylobacterium extorquens ATCC 55366 with succinate as a sole carbon source. The result using a pH-stat-based fed-batch fermentation showed that succinate in the medium was accumulated with severe enzyme degradation in the latter part of the cultivation. To elucidate the effects of enzyme expression conditions on the productivity and final concentration of the enzyme, fed-batch cultivations with various induction OD600 values (5, 15, and 25) and specific growth rates (0.03, 0.05, and 0.1 h-1) were conducted. Feedforward-feedback control strategy based on the exponential feeding considering actual growth rate was designed and implemented. The induction OD and specific growth rate at the optimized condition for the production of FDH were 15 and 0.05 h-1 where the specific enzyme activity, the enzyme production, and volumetric productivity were 308.3 U/g WCW, 17758 U/L, and 381.9 U/L/h, respectively. The fed-batch cultivation with controlled growth rate and induction time enables efficient production of FDH, thus opening an economical and green route for waste CO utilization.