Isolation, purification, and mass spectrometry identification of the enzyme involved in citrus flavor (+)‐valencene biotransformation to (+)‐nootkatone by Yarrowia lipolytica

Abstract

AbstractBACKGROUND(+)‐Nootkatone is a highly valuable sesquiterpene compound that can be used as an aromatic in the food industry because of its grapefruit flavor and low sensory threshold. The unconventional yeast Yarrowia lipolytica has many unique physical and chemical properties, metabolic characteristics, and genetic structure, which has aroused the interest of researchers. Previous research showed that Y. lipolytica possesses the ability to transform the sesquiterpene (+)‐valencene to (+)‐nootkatone. The aim of this study was to isolate, purify, and identify the enzyme involved in the (+)‐valencene bioconversion to (+)‐nootkatone by Y. lipolytica.RESULTSIn this study, ultrasonic‐assisted extraction, ammonium sulfate precipitation, anion‐exchange chromatography, and gel‐filtration chromatography were used to separate and purify the enzyme involved in the (+)‐valencene bioconversion by Y. lipolytica. The protein was identified as aldehyde dehydrogenase (ALDH) (gene0658) using sodium dodecyl sulfate polyacrylamide gel electrophoresis and liquid chromatography–tandem mass spectrometry analysis. The ALDH had the highest activity when the pH value was 6.0 and the temperature was 30 °C. The activity of ALDH was significantly stimulated by ferrous ions and inhibited by barium, calcium, and magnesium ions.CONCLUSIONThis is the first time that ALDH was found to participate in (+)‐valencene biotransformation by Y. lipolytica. It may be involved in regulating the microbial transformation of (+)‐valencene to (+)‐nootkatone through redox characteristics. This study provides a theoretical basis and reference for the biological synthesis of citrus flavor (+)‐nootkatone. © 2023 Society of Chemical Industry.