Halohydrin dehalogenase immobilization in magnetic biochar for sustainable halocarbon biodegradation and biotransformation

Abstract

Regarding the fact that halohydrin dehalogenase (HHDH) displays great potential for both biotransformation and biodegradation, developing immobilized HHDH that is suitable for those applications will be of great importance. Herein, the functionalized magnetic biochar was prepared for efficient enzyme immobilization, easy separation, and reuse. The immobilized halohydrin dehalogenase (HheC) was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM). The results showed that the relative enzyme activity retention was 85% upon immobilization in biochar (HheC-N-MBC600). After 70 days of storage at 4 °C, the HheC-N-MBC600 retained 50% of its initial activity, while only 8% of the activity was retained for the free enzyme. HheC-N-MBC600 displayed a strong organic solvent tolerance as it retained activity above 92% after incubation in 50% organic solvent for 12 h. Moreover, the immobilized catalyst retained more than 70% activity after a consecutive 30 cycles of reuse, indicating excellent recyclability of the immobilized biocatalyst. Moreover, the immobilized enzyme displayed the same enantioselective behavior as the free enzyme. Together with the immobilized epoxide hydrolyase (EchA-MBC600), HheC-N-MBC600 completely converted 1,3-dichloro-2-propanol (1,3-DCP) to a nontoxic compound. Our results showed that the immobilized HheC-N-MBC600 could be a green and industrially viable tool to degrade halogenated compounds and make useful chiral compounds.