Covalent immobilization of halohydrin dehalogenase for efficient synthesis of epichlorohydrin in an integrated bioreactor

Abstract

Halohydrin dehalogenase (HHDH)-mediated dehalogenation of 1,3-dichloro-2-propanol (1,3-DCP) is a key step in the chemoenzymatic synthesis of epichlorohydrin (ECH) from glycerol. In this study, a covalent immobilization strategy was employed to enhance the stability of Agrobacterium tumefaciens HHDH using epoxy resin ES-103B as a carrier. Under optimal conditions, the activity recovery of ES-103B-immobilized HHDH (HHDH@ES-103B) was 62.4% and the specific activity was 1604 U/g. The HHDH@ES-103B exhibited excellent thermostability, with a half-life of 68.6 days at 40°C, which is 8.0-times higher than that of the free HHDH. A semicontinuous biotransformation of 1,3-DCP to ECH was performed using HHDH@ES-103B as biocatalyst in a recirculating packed bed reactor (RPBR), resulting in an ECH yield of 94.2%, with an average productivity of 5.2 g/L/h. The RPBR system exhibited a high operational stability and even after 50 cycles of reaction, it retained > 90% of the initial conversion. Furthermore, an integrated bioprocess based on in situ product recovery (ISPR) was developed in RPBR to overcome product inhibition. The integrated bioreactor equipped with an external macroporous adsorption resin HZD-9 column led to another 1.6-fold increase in ECH productivity to 8.46 g/L/h. This improved stability and reusability of HHDH@ES-103B demonstrated its potential for the biotransformation of 1,3-DCP to ECH. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:784-792, 2018.

Biodegradation of 1,2,3-Trichloropropane to Valuable (S)-2,3-DCP Using a One-Pot Reaction System

“…We tested the effect of the amount of resin HZD-9 (%) (w/v) on enzyme activity. HZD-9 was applied previously to selectively remove ECH [13,14]. As shown in Figure 3, no significant effect of HZD-9 (up to 5%) on the enzymatic activity was observed.…”

“…To overcome this limitation, ECH removal was proposed as a possible solution. For this, an aqueous-organic biphasic system and resin-mediated product removal were successfully applied in some cases [8,13,14]. In this study, we evaluated the suitability of the above-mentioned approaches to solve the racemization problem.…”

“…In our case, the resin-mediated product removal was proved more promising than the bi-phasic system. Since resin-based ECH removal for cell-free system has been successfully applied to the biotransformation of 1,3-DCP to ECH [13,14], resin (HZD-9) mediated in situ product removal was considered for the subsequent experiments. In this study, we evaluated the suitability of the above-mentioned approaches to solve the racemization problem.…”

“…On the other hand, resin-based in situ product removal could be another option to resolve such an inhibition. The resin HZD-9 has been successfully applied in the synthesis of ECH from 1,3-DCP catalyzed by HheC [13,14].…”

The Impact of Recent Developments in Technologies which Enable the Increased Use of Biocatalysts

“…The use of epoxy‐functionalized resins is advantageous because of their ease of use. They have been used to immobilize halohydrin dehydrogenases directly from the cell lysate, without need for prior purification . Epoxy functionalized silica has been used as an efficient support for lipases in the resolution of ibuprofen esters …”