Different aspects of biocatalysis are discussed with a view to obtaining products in a practical way using microorganisms and enzymes in catalytic amounts but as if they were organic reagents. A limited number of reactions catalysed by microbial reagents have been examinded according to the following classes: C-C bond formation, including the reaction catalyzed by aldolases, enantiomeric oxynitrilases, and decarboxylases. Oxidations promoted by microorganisms leading to Bayer-Williger-type products and hydroxylation at saturated carbon also includes the production of...