Enzyme and Microbial Technology, Vol.86, 34-38, 2016
Enhanced bioconversion rate and released substrate inhibition in (R)-phenylephrine whole-cell bioconversion via partial acetone treatment
An approach was developed to enhance the efficiency for the bioconversion of 1-(3-hydroxyphenyl)-2-(methyamino)-ethanone to (R)-phenylephrine. The strain Serratia marcescens N10612, giving the benefit of 99% enantiomeric excess in (R)-PE conversion, was used. The fermentation was devised to harvest cells with high hydrophobic prodigiosin content inside the cells. Then, the partial acetone extraction was applied to remove prodigiosin from the cells. The treatment was found to increase the cells conversion rate without loss of the cells NADPH redox system. When using 50% (v/v) acetone for 5 min, the processed cells can give a specific conversion rate of 16.03 mu mol/h/g-cells. As compared the treated cells with cells under the basal medium, the maximum reaction rate (V-max) increased from 6.69 to 10.27 (mu mol/h/g-cells), the dissociation constant (K-m) decreased from 0.236 to 0.167 mM and the substrate inhibition constant (K-si) increased from 0.073 to 1.521 mM. The 20-fold increase in substrate inhibition constant referred to a great release from the substrate inhibition for the use of S. marcescens N10612 in the bioconversion, which would greatly benefit the bioconversion to be industrialized. (C) 2016 Published by Elsevier Inc.