Optimization of Ultrasonic Extraction of Key Enzymes for Trans-dihydrocarvone Transformation in Klebsiella sp. O852

In this study, the cells of Klebsiella sp. O852 were disrupted by ultrasonic extraction. The location and the conversion conditions of the key enzymes for the conversion of limonene to trans-dihydrocarvone were investigated. Then, the effects of ultrasonic time, material-liquid ratio, and amplitude on cell disruption were studied using the single factor experiments. Additionally, the Box-Behnken central combination test was designed to determine the optimal extraction conditions. The results showed that the enzyme was an intracellular enzyme. The optimal cultivation time was 8 h, which was the mid-logarithmic phase of cell growth. The optimum conversion time was 4 h, and the highest enzyme activity was obtained in phosphate buffer solution. The single factor experiments and response surface test showed that the optimal ultrasonic time was 21 min, material-liquid ratio was 1:13, and amplitude was 36%. And the content of the enzyme activity was (40.97±2.02) U/g under these optimal conditions. This study would provide a reference for further study on the purification and enzymatic properties of this enzyme.