Biodegradation of 1,2,3-trichloropropane to valuable (S)-2,3-DCP using a one-pot reaction system

Abstract

1,2,3-trichloropropane (TCP) being one of the important environmental pollutants, has drawn significant concern due to its highly toxic and carcinogenic effects. In this study, we built a one-pot reaction system in which immobilized haloalkane dehalogenase (DhaA31) and halohydrin dehalognase (HheC) were used to catalyze the recalcitrant TCP to produce 2,3-dichloro-1-propanol (2,3-DCP) by removing epichlorohydrin (ECH). Since HheC displays a high R enantiopreference toward 2,3-DCP, the production of enantiopure (S)-2,3-DCP was expected. However, the enantioselective resolution of (R,S)-2,3-DCP by HheC was greatly inhibited by the circular reaction occurring between the product ECH and 1,3-dichloro-2-propanol (1.3-DCP). To resolve this problem, HZD-9 resin-based in situ product removal was implemented. Under the optimized conditions, TCP was completely consumed, resulting in optically pure (S)-2,3-DCP with enantiomer excess (e.e) > 99% and 40% yield (out of the 44% theoretical maximum). The scale-up resin-integrated reaction system was successfully carried out in 0.5 L batch reactor. Moreover, the system could be reused for 6 rounds with 64% of original activity retained, showing that it could be applied in the treatment of large volumes of liquid waste and producing enantiopure (S)-2,3-DCP.