Enhancement of (S)-2,3-dichloro-1-propanol production by recombinant whole-cell biocatalyst in n-heptane-aqueous biphasic system.

The enantioselective resolution of (R,S)-2,3-dichloro-1-propanol ((R,S)-DCP) to (S)-DCP by whole cells of a recombinant Escherichia coli expressing halohydrin dehalogenase (HHDH) activity was limited by product inhibition. To solve this problem to improve the productivity of (S)-DCP, an n-heptane-aqueous biphasic system was adopted in this work. The influential operational parameters including phase volumetric ratio, buffer pH and reaction temperature were optimized. Under the optimal reaction conditions, significant improvements of substrate concentration and biocatalyst productivity (375 mM and 7.64 mmol (S)-DCP g(-1) cell) were achieved in this n-heptane-aqueous biphasic system compared with aqueous single-phase system (150 mM and 2.97 mmol g(-1)cell). The scale-up biosynthesis of (S)-DCP was successfully performed in a 2-L stirred reactor, resulting in a 128.8 mM (S)-DCP with enantiomeric excess of 99.1% and average productivity of 2.07 g (S)-DCPL(-1) h(-1), respectively.