2E, 2E, citral and geraniol as precursors of geranial form acyloins enzymatically by reaction with activated acetate during fermentation by Mucor circinelloides CBS 39468. The acyloins were reduced immediately by the fungus to (2S,3R)-diols. Reduction of the aldehyde group, including hydrogenation of the conjugated C-C double bond, hydroxylation of these alcohols and of the formed diols and some cyclizations are found as side reactions.