biocatalytic methods for the stereoselectivereduction of cyclic prochiral 1,3-diketones for the production of optically active β -hydroxyketones and/or 1,3-diols. The recombinant ketoreductase KRED1-Pglu (formulated as purified catalyst) and whole cells of wild type Escherichia coli DE3 Star were used as biocatalysts, displaying different and sometimes complementary stereoselectivity, thus allowing the preparation