Studies on the Catalytic Properties of Crude Freeze-Dried Preparations of <i>Yarrowia lipolytica</i> Extracellular Lipases for Geranyl Ester Derivative Synthesis

• Main Authors: Karina Jasińska, Bartłomiej Zieniuk, Dorota Nowak, Agata Fabiszewska
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Biomolecules
• Subjects: antibacterial; antioxidant; biocatalyst; cryoprotectant; esterification; freeze-drying
• Online Access: https://www.mdpi.com/2218-273X/11/6/839

The study aimed to evaluate the impact of selected factors of the freeze-drying process on the hydrolytic and synthetic activity of the extracellular lipases of <i>Y. lipolytica</i> KKP 379 and to attempt the use of the crude enzyme preparation as a biocatalyst in the synthesis of geranyl 4-hydroxyphenylpropanoate. Antioxidant and antibacterial properties of the geranyl ester derivative were also investigated in order to evaluate their usefulness as a novel food additive. The studies confirmed that freeze-drying was an effective method of dehydrating yeast supernatant and allowed for obtaining lyophilizates with low water activity from 0.055 to 0.160. The type and concentration of the additive (2–6% whey protein hydrolyzate, 0.5% and 1% ammonium sulphate) had a significant effect on the hydrolytic activity of enzyme preparations, while the selected variants of drying temperature during the freeze-drying process were not significant (10 °C and 50 °C). Low yield of geranyl 4-hydroxyphenylopropionate was shown when the lyophilized supernatant was used (5.3%), but the yield of ester synthesis increased when the freeze-dried <i>Y. lipolytica</i> yeast biomass was applied (47.9%). The study confirmed the antioxidant properties of the synthesized ester by the DPPH<b>•</b> and CUPRAC methods, as well as higher antibacterial activity against tested bacteria than its precursor with 0.125 mM MIC (minimal inhibitory concentration) against <i>L. monocytogenes</i>.