Abstract
l-Lyxose was prepared from ribitol by a new method comprising a potent microbial oxidation reaction to convert ribitol to l-ribulose, epimerization of the l-ribulose to l-xylulose, and isomerization of the l-xylulose to produce l-lyxose. The complete transformation of ribitol to l-ribulose was achieved using washed cells of Acetobacter aceti IFO 3281 at high substrate concentrations ranging from 5–20%. The l-ribulose produced was then used as the substrate for the production of l-lyxose using immobilized l-rhamnose isomerase (l-RI) of Pseudomonas sp. strain LL172 and immobilized d-tagatose 3-epimerase (d-TE) of recombinant Escherichia coli JM 105. At equilibrium, the yield of l-lyxose from l-ribulose was determined to be about 60%, and the product could be isolated easily from the reaction mixture after degradation of ketoses using Pseudomonas sp. 172a. Following various product purification steps, about 5.0 g l-lyxose crystals were recovered from 10.0 g ribitol in a flask reaction. The crystallized product was finally identified by HPLC, IR spectrum, NMR, and optical rotation measurements.
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