earticle

영어

The recombinant Corynebacterium glutamicum-based biocatalyst, expressing the chnB gene encoding cyclohexanone monooxygenase of Acinetobacter calcoaceticus NCIMB 9871, w as engineered to increase transport efficiency of lipophilic substrates into the cells. Oxygenation of
2-(2’-acetoxyethyl)cyclohexanone into R-7-(2’-acetoxyethyl)-2-oxepanone by the recombinant C. glutamicum followed Michaelis-Menten kinetics. The Vmax and KS values were estimated 96.8 U/g CDW and 0.98 mM, respectively. The Vmax value was comparable to that of cyclohexanone oxygenation, whereas the KS value was almost 8-fold higher. The KS value
of 2-(2’-acetoxyethyl)cyclohexanone oxygenation could be reduced to around 70% without influencing Vmax by engineering cell envelop of C. glutamicum with ethambutol, which inhibits arabinosyltransferase involved in the synthesis of cell wall arabinogalactan layer and mycolate layer. The same effect of ethambutol treatment on KS of the recombinant C. glutamicum
biocatalyst was observed in oxygenation of ethyl 2-cyclohexanoneacetate. Thus, it was concluded that transport efficiency of medium to bulky lipophilic substrates into C. glutamicum biocatalysts could be enhanced via engineering their arabinogalactan and mycolate layers in cell envelops.