RESUMO
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-AIase) gene from Alicyclobacillus hesperidum and the d-lyxose isomerase (d-LIase) gene from Thermoflavimicrobium dichotomicum were cloned and co-expressed in Escherichia coli, resulting in recombinant cells harboring the vector pCDFDuet-Alhe-LAI/Thdi-DLI. The co-expression system exhibited optimal activity at a temperature of 70⯰C and pH 6.0, and the addition of Co2+ enhanced the catalytic activity by 27.8-fold. The system containing 50â¯g L-1 of recombinant cells were relatively stable up to 55⯰C. The co-expression system (50â¯g L-1 of recombinant cells) afforded 20.9, 39.7, and 50.3â¯g L-1 of l-ribose from initial l-arabinose concentrations of 100, 300, and 500â¯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-AIase and d-LIase genes.