Biosynthesis of (R)-γ-Decanolactone in the Yeast Sporobolomyces odorus

Addition of [9,10-2H2]oleic acid to cultures of the yeast Sporobolomyces odorus led to the formation of labeled (R)-γ-decanolactone and both enantiomers of (Z)-6-γ-dodecenolactone and γ-dodecanolactone. The labeling patterns of these lactones were estimated by a quantitative gas chromatography/mass spectrometry method, suitable for ring-labeled lactones. For the first time, there is strong evidence of oleic acid being a genuine precursor of the important aroma compound (R)-γ-decanolactone. On the basis of the presented and former results, a new biosynthetic pathway of this compound is proposed. Starting with a strict enantioselective (R)-12-hydroxylation of oleic acid as an initial step, the following β-oxidation led to the lactone. In addition, biosynthetic aspects of the formation of (Z)-6-γ-dodecenolactone and γ-dodecanolactone in S. odorus are discussed. Keywords: γ-Lactones; aroma compound; (R)-γ-decanolactone; [9,10-2H2]oleic acid; Sporobolomyces odorus; biosynthesis