The technology of microbial transformations is concerned with harnessing the enzymes of microorganisms to catalyze useful reactions of organic compounds. Microbial enzymes are well known for their abilities to hydrolyze, oxidize, reduce, and otherwise change the structures of organic chemicals. This review summarizes important historical applications of microbes to transform steroids, amino acids, antibiotics, sugars, and others structural classes of compounds and introduces applications of microorganisms and their enzymes as reagents in synthetic organic chemistry. It covers reactions including oxidations (hydroxylation, dioxygenation, dehydrogenation, β‐oxidation, and Baeyer‐Villiger oxidation), reductions (of ketones, double bonds, and carboxylic acids), hydrolyses (esters, amides, and nitriles), condensations (acyloin, aldolase, and carboxylation), amination and deamination, dehydration,
N
‐ and
O
‐dealkylation, decarboxylation, conjugations (
N
‐acetylation,
O
‐phosphorylation, and
O
‐adenylylation) and isomerization. The methodology of microbial transformations is also described. Vol. 16, pp. 611–627, 100 refs. to September 1993.