Overexpression and characterization of CCD4 from Osmanthus fragrans and β-ionone biosynthesis from β-carotene in vitro

In this study, a recombinant carotenoid cleavage dioxygenase 4 was produced from Osmanthus fragrans by E. coli under different bacterial growth conditions and used to develop a biotechnological method for preparation of natural β-ionone from β-carotene. β-ionone was analyzed by HPLC and OfCCD4 activity was measured based on concentration change of β-ionone. At pH 8.0 and 35 °C, the greatest activity of the purified recombinant protein was 14.3 U/mg and the maximum concentration of β-ionone was 71.186 mg/L within 1 h. Both the enzyme activity and the concentration of β-ionone could increase by nearly 6 times with addition of 9% Triton X-100 and 2% liquid paraffin.