title: Continuous production of gluconic acid and sorbitol from Jerusalem artichoke and glucose using an oxidoreductase of Zymomonas mobilis and inulinase.
abstract: Gluconic acid and sorbitol were simultaneously produced from glucose and Jerusalem artichoke using a glucose-fructose oxidoreductase of Zymomonas mobilis and inulinase. Inulinase was immobilized on chitin by cross-linking with glutaraldehyde. Cells of Z. mobilis permeabilized with toluene were coimmobilized with chitin-immobilized inulinase in alginate beads. The optimum amounts of both chitin-immobilized inulinase and permeabilized cells for coimmobilization were determined, and operational conditions were optimized. In a continuous stirred tank reactor operation, the maximum productivities for gluconic acid and sorbitol were about 19.2 and 21.3 g/L/h, respectively, at the dilution rate of 0.23 h(-1) and the substrate concentration of 20%, but operational stability was low because of the abrasion of the beads. As an approach to increase the operational stability, a recycle packed-bed reactor (RPBR) was employed. In RPBR operation, the maximum productivities for gluconic acid and sorbitol were found to be 23.4 and 26.0 g/L/h, respectively, at the dilution rate of 0.35 h(-1) and the substrate concentration of 20% when the recirculation rate was fixed at 900 mL/h. Coimmobilized enzymes were stable for 250 h in a recycle packed-bed reactor without any loss of activity, while half-life in a continuous stirred tank reactor (CSTR) was observed to be about 150 h.
authors.affiliation: Department of Biological Science and Engineering, Korea Advanced Institute of Science and Technology, Cheongyang, Seoul 130-650, Korea.
authors.forename: D M
authors.initials: DM
authors.lastname: Kim
authors.forename: H S
authors.initials: HS
authors.lastname: Kim