Expression and characterization of a 9-cis-epoxycarotenoid dioxygenase from Serratia sp. ATCC 39006 capable of biotransforming isoeugenol and 4-vinylguaiacol to vanillin

摘要

A 9-cis-epoxycarotenoid dioxygenase gene from Serratia sp. ATCC 39,006 ( SeNCED ) was overexpressed in soluble form in E.coli. SeNCED showed the maximum activity at 30?°C and pH 8.0, and it was stable relatively at range of pH 5–10 and temperature of 20?°C to 30?°C. SeNCED effectively catalyzes the side chain double bond cleavage of isoeugenol and 4-vinylguaiacol to vanillin. The kinetic constant K_m values toward isoeugenol and 4-vinylguaiacol were 18.92?mM and 6.31?mM and V _max values were 50.73?IU/g and 4.77?IU/g, respectively. Moreover, the SeNCED exhibited an excellent organic solvent tolerance and the enzyme activity was substantially improved at presence of 10% of trichloromethane. The produced vanillin was achieved at an around 0.53?g/L (3.47?mM) and 0.33?g/L (2.17?mM) after 8?h reaction at 4?mM of isoeugenol and 4-vinylguaiacol, respectively, using transformed Escherichia coli cells harboring SeNCED in the presence of trichloromethane.