Factors Affecting the Yield in Formation of Fat-Derived Fragrance Compounds by Yarrowia lipolytica Yeast

Abstract

Yarrowia lipolytica belongs to the group of microorganisms widely used in scientific research for environmentally friendly biotransformation reactions. This yeast produces a number of compounds important from the point of view of the food and cosmetics industries, including flavor and fragrance compounds. The results of selected studies on the possibility of biosynthesis of fat-derived fragrances, namely gamma-decalactone (GDL) and hexanal, are presented in this article. The wild-type Yarrowia yeast strain KKP379 and the LOX/HPL mutant were used in the studies. With the aim of improving the synthesis yield of both aroma compounds, parameters such as concentration of lipid substrate, the type of culture medium, and the addition of surfactants, and, not yet verified in the available literature in this context, the concentration of inoculum, the addition of heptane, and the emulsification of culture medium were analyzed. The research showed that the concentration of the lipid substrate and the degree of emulsification of the medium had a significant influence on the amount of GDL production. The higher the content of castor oil in the medium, the higher the concentration of the synthesized aroma compound, with a significant extension of the reaction time. By varying the concentration of castor oil in the medium in the range of 10–100 g/L, an increase in the lactone concentration was obtained from 1.86 ± 0.15 g/L to 3.06 ± 0.2 g/L, with a simultaneous extension of the reaction from 3 to 7 days. It is noteworthy that the additional application of the emulsification of the medium allowed the efficiency of GDL biosynthesis to be significantly increased by over 2 g/L to a lactone concentration of approximately 5.25 ± 0.10 g/L. This is one of the highest reported concentrations for the production of this biofragrance by the wild strain. In the case of hexanal synthesis, the increase of the concentration of linoleic acid in the culture medium from 25 g/L to 100 g/L resulted in a 5-fold higher concentration of aldehyde in the cell extract. At a higher concentration of the lipid substrate in the medium, the modified whole-cell catalyst showed a higher activity of lipoxygenase.