Electrochemical reduction of xylose to xylitol by whole cells or crude enzyme of Candida peltata.
In this study, whole cells and a crude enzyme of Candida peltata were applied to an electrochemical bioreactor, in order to induce an increment of the reduction of xylose to xylitol. Neutral red was utilized as an electron mediator in the whole cell reactor, and a graphite-Mn(IV) electrode was used as a catalyst in the enzyme reactor in order to induce the electrochemical reduction of NAD(+) to NADH. The efficiency with which xylose was converted to xylitol in the electrochemical bioreactor was five times higher than that in the conventional bioreactor, when whole cells were employed as a biocatalyst. Meanwhile, the xylose to xylitol reduction efficiency in the enzyme reactor using the graphite-Mn (IV) electrode and NAD(+) was twice as high as that observed in the conventional bioreactor which utilized NADH as a reducing power. In order to use the graphite-Mn(IV) electrode as a catalyst for the reduction of NAD(+) to NADH, a bioelectrocatalyst was engineered, namely, oxidoreductase (e.g. xylose reductase). NAD(+) can function in this biotransformation procedure without any electron mediator or a second oxidoreductase for NAD(+)/NADH recycling.
Park
Sun Mi
SM
Department of Biological Engineering, Seokyeong University, Seoul 136-704, Republic of Korea.
Sang
Byung In
BI
Park
Dae Won
DW
Park
Doo Hyun
DH
D019149:Bioreactors; D001709:Biotechnology / Q000379:methods; D002175:Candida / Q000166:cytology* / Q000201:enzymology*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D006108:Graphite; D008345:Manganese; D009499:Neutral Red / Q000378:metabolism; D010084:Oxidation-Reduction; D014993:Xylitol / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
D009499:Neutral Red; D008345:Manganese; D006108:Graphite; D014994:Xylose; D014993:Xylitol