Recombinant bacterial cells as efficient biocatalysts for the production of nucleosides.

The preparation of nucleosides as well as their base-modified analogues using purified nucleoside phosphorylase enzymes or, more conveniently, using whole bacterial cells is described. The development of genetically modified strains of Escherichia coli, able to over-produce Uridine-phosphorylase and Purine-nucleoside-phosphorylase in the same cells, improves the specific biocatalytic activity and the consequent industrial scale approach.