Identification and characterization of carveol dehydrogenases from Klebsiella sp. O852

Natural carvone is widely utilized in the food industry, cosmetics, agrochemicals, and pharmaceuticals due to its unique sensory characteristics and numerous biological effects. The enzyme carveol dehydrogenase catalyzes the oxidation reaction transforming carveol into carvone. In the present study, genome-based analysis of Klebsiella sp. O852 enabled the identification of four potential alcohol dehydrogenase (ADH) genes involved in the bioconversion process from carveol to carvone. These candidate genes were then heterologously expressed in Escherichia coli BL21(DE3), followed by purification and biochemical characterization of the recombinant proteins. All KlebADHs (ADHs from Klebsiella sp. O852) except KlebADH4 demonstrated carveol dehydrogenase activity and effectively catalyzed the conversion of carveol into carvone. Enzymatic experiments revealed optimal temperatures of 30–40 °C and an optimal pH of 9.0 for KlebADH3, KlebADH5, and KlebADH6. These enzymes were active with both NADP + and NAD + . Some organic solvents and metal ions, particularly Cu 2+ and Mn 2+ , significantly inhibited enzyme activity. Additionally, kinetic experiments indicated that KlebADH3 possessed the highest catalytic efficiency. This study expands the enzyme resources available for synthesizing carvone-derived compounds and provides a theoretical foundation for regulating enzymatic catalytic properties and improving carvone production.