PRODUCTION OF LACTONES AND PEROXISOMAL BETA-OXIDATION IN YEASTS

Among aroma compounds interesting for the food industry, lactones may be produced by biotechnological means using yeasts. These microorganis ms are able to synthesize lactones de novo or by biotransformation of fatty acids with higher yields. Obtained lactone concentrations are co mpatible with industrial production, although detailed metabolic pathw ays have not been completely elucidated. The biotransformation of rici noleic acid into gamma-decalactone is taken here as an example to bett er understand the uptake of hydroxy fatty acids by yeasts and the diff erent pathways of fatty acid degradation. The localization of ricinole ic acid beta-oxidation in peroxisomes is demonstrated. Then the regula tion of the biotransformation is described, particularly the induction of peroxisome proliferation and peroxisomal beta-oxidation and its re gulation at the genome level. The nature of the biotransformation prod uct is then discussed (4-hydroxydecanoic acid or gamma-decalactone), b ecause the localization and the mechanisms of the lactonization are st ill not properly known. Lactone production may also be limited by the degradation of this aroma compound by the yeasts which produced it. Th us, different possible ways of modification and degradation of gamma-d ecalactone are described.