The whole-cell immobilization of D-hydantoinase-engineered Escherichia coli   for D-CpHPG biosynthesis

Background: _D-Hydroxyphenylglycine is considered to be an important chiral molecular building-block of antibiotic reagents such as pesticides, and β-lactam antibiotics. The process of its production is catalyzed by _D-hydantoinase and _D-carbamoylase in a two-step enzyme reaction. How to enhance the catalytic potential of the two enzymes is valuable for industrial application. In this investigation, an Escherichia coli strain genetically engineered with _D-hydantoinase was immobilized by calcium alginate with certain adjuncts to evaluate the optimal condition for the biosynthesis of _D-carbamoyl-p-hydroxyphenylglycine (_D-CpHPG), the compound further be converted to _D-hydroxyphenylglycine (_D-HPG) by carbamoylase.
Result: The optimal medium to produce _D-CpHPG by whole-cell immobilization was a modified Luria-Bertani (LB) added with 3.0% (W/V) alginate, 1.5% (W/V) diatomite, 0.05% (W/V) CaCl₂ and 1.00 mM MnCl₂. The optimized diameter of immobilized beads for the whole-cell biosynthesis here was 2.60 mm. The maximized production rates of _D-CpHPG were up to 76%, and the immobilized beads could be reused for 12 batches.
Conclusions: This investigation not only provides an effective procedure for biological production of _D-CpHPG, but gives an insight into the whole-cell immobilization technology. © 2016 Pontificia Universidad Católica de Valparaíso. Production and hosting by Elsevier B.V. All rights reserved.

Keywords
Calcium alginate; _D-Carbamoyl-p-hydroxyphenylglycine; _D-Hydantoinase; _D-Hydroxyphenylglycine; Immobilization; Whole cell