Lipase Induction in Yarrowia lipolytica for Castor Oil Hydrolysis and Its Effect on γ-Decalactone Production

gamma-Decalactone is an aromatic compound of industrial interest, resulting from the biotransformation of ricinoleic acid, the major constituent of castor oil. In order to increase the availability of the substrate to the cells for the aroma production, castor oil previously hydrolyzed can be used. This hydrolysis may be promoted by enzymatic action, more specifically by lipases. In this work, the influence upon the aroma production of the lipase produced by Yarrowia lipolytica, a microorganism able to carry out the biotransformation, was studied. In a first approach, lipase induction conditions were analyzed using different Y. lipolytica strains and culture conditions, such as the inoculation mode of the lipase production medium. Lipase production was not affected by the cells centrifugation, so this step was eliminated, reducing the time and phases of the process. Moreover, Y. lipolytica W29 was shown to be the most adequate strain for lipase production. To investigate the importance of castor oil hydrolysis, the pre-addition of an inducer of lipase production (olive oil) to the biotransformation medium was tested. Results showed that the highest aroma production (1,600 mg L-1) was obtained without a lipase inducer. However, the pre-induction of lipase decreased the lag phase for gamma-decalactone secretion.