Immobilized Aspergillus niger epoxide hydrolases: Cost-effective biocatalysts for the prepation of enantiopure styrene oxide, propylene oxide and epichlorohydrin

This study aimed to prepare robust immobilized epoxide hydrolase (EH) preparations for asymmetric hydrolysis of racemic epoxides such as styrene oxide, propylene oxide and epichlorohydrin. For this purpose, Aspergillus niger EH was immobilized onto Lewatit® VP OC 1600 support by adsorption, modified Florisil® and Eupergit® C supports by covalently. The suitability of the supports was examined for protein binding capacity and rate of racemic styrene oxide hydrolysis. The protein-activity recovery yields were 75–85%, 82–78% and 90–75%, respectively for EH immobilized onto Lewatit® VP OC 1600, modified Florisil® and Eupergit® C supports. All A. niger EH preparations catalyzed preferentially hydrolysis of (R)-epoxides. Although enantiomeric excess values of all the tested epoxides were 99%, the highest enantiopure epoxide yields were obtained as 48% for (S)-styrene oxide by the immobilized EHs onto modified Florisil® and Eupergit® C. The highest diol yield was obtained as 78% for 3-chloro-1,2-propanediol, however, its enantiomeric excess value was 28.2%. Enantioselectivity of A. niger EH was improved with the preparation of mentioned immobilized forms. The highest enantioselectivity value was obtained as 95 toward styrene oxide by A. niger EH immobilized onto modified Florisil®. The results of reusability studies show that the immobilized EH preparations offer feasible potentials for the preparation of enantiopure epoxides than that of free form.

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► All the Aspergillus niger EH preparations catalyze preferentially hydrolysis of (R)-epoxides.
► Enantioselectivity of A. niger EH is generally enhanced upon the immobilization.
► The immobilized EH preparations are more promising and effective catalysts toward its free form.