Lactones are known to be flavour compounds for many foodstuffs. Microorganisms are able to produce these molecules which may substitute plant flavours. Sporidiobolus salmonicolor is one of the most studied microorganisms for the production of lactones. However very few is known about the different pathways used by this yeast. Lactones biosynthesis is related to fatty acids oxidation. Sporidiobolus salmonicolor is able to produce a family of gamma- and delta-lactones. These have an asymetric carbon and two enantiomers (R) or (S) may be synthetized. In this work we present that the enantiomeric excess is rather constant with the medium composition or the growth stage but depends on the lateral chain length. Gamma decalactone produced on a glucose mineral medium is optically pure (100% R), and gamma dodecalactone is found as a racemic. Hypothesis are proposed to explain such observations, based on chirality of precursors or stereospecificity of catabolic enzymes. The understanding of pathways may permit to compare flavour production by plants and by Sporidiobolus salmonicolor.