Presumptive involvement of methyl ricinoleate β‐oxidation in the production of γ‐decalactone by the yeast Pichia guilliermondii

Production of γ‐decalactone by yeasts from fatty acids has been reported but little is known about the mechanisms involved in this process. This paper provides information about the mechanisms involved in the production of γ‐decalactone by Pichia guilliermondii in the presence of a fatty acid methyl ester. Culturing of P. guilliermondii in media containing methyl ricinoleate (12(R)‐hydroxy‐9(Z)‐octadecenoic acid) revealed a coordinated induction of β‐oxidation activities and γ‐decalactone production. However, no γ‐decalactone synthesis was noted when methyl ricinoleate was changed into methyloleate or methyl linoleate, even though these fatty acid methyl esters are able to induce β‐oxidation activities in P. guilliermondii. These observations led us to conclude that methyl ricinoleate is an inducer of β‐oxidation and is probably the substrate for γ‐decalactone production. The fatty acid ester β‐oxidation should be involved, at least in part, in this production.