Production of L-ribose from L-arabinose by co-expression of L-arabinose isomerase and D-lyxose isomerase in Escherichia coli

L-Ribose is an important pharmaceutical intermediate that is used in the synthesis of numerous antiviral and anticancer drugs. However, it is a non-natural and expensive rare sugar. Recently, the enzymatic synthesis of L-ribose has attracted considerable attention owing to its considerable advantages over chemical approaches. In this work, a new strategy was developed for the production of L-ribose from the inexpensive starting material L-arabinose. The L-arabinose isomerase (L-Alase) gene from Alicyclobacillus hesperidum and the D-lyxose isomerase (D-Llase) gene from Thermofiavimicrobiwn clichotomicum were cloned and co-expressed in Escherichia colt, resulting in recombinant cells harboring the vector pCDFDuet-Alhe-LAI/Thdi-DLI. The co-expression system exhibited optimal activity at a temperature of 70 degrees C and pH 6.0, and the addition of Co2+ enhanced the catalytic activity by 27.8-fold. The system containing 50 g L-1 of recombinant cells were relatively stable up to 55 degrees C. The co-expression system (50 g L-1 of recombinant cells) afforded 20.9, 39.7, and 50.3 g L-1 of L-ribose from initial L-arabinose concentrations of 100, 300, and 500 g L-1, corresponding to conversion rate of 20.9%, 13.2%, and 10.0%, respectively. Overall, this study provides a viable approach for producing L-ribose from L-arabinose under slightly acidic conditions using a co-expression system harboring L-Alase and D-Llase genes.