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

Backgroundd-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.ResultsThe 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.ConclusionsThis investigation not only provides an effective procedure for biological production of d-CpHPG, but gives an insight into the whole-cell immobilization technology.