Biosynthesis of Ethyl (S)-4-Chloro-3-Hydroxybutanoate by NADH-Dependent Reductase from E. coli CCZU-Y10 Discovered by Genome Data Mining Using Mannitol as Cosubstrate

The reductase (PgCR) from recombinant Escherichia coli CCZU-Y10 displayed high reductase activity and excellent stereoselectivity for the reduction of ethyl 4-chloro-3-oxobutanoate (COBE) into ethyl ( S )-4-chloro-3-hydroxybutanoate (( S )-CHBE). To efficiently synthesize ( S )-CHBE (>99 % enantiomeric excess (ee)), the highly stereoselective bioreduction of COBE into ( S )-CHBE with the whole cells of E. coli CCZU-Y10 was successfully demonstrated in a dibutyl phthalate-water biphasic system. The appropriate ratio of the organic phase to water phase was 1:1 ( v / v ). The optimum reaction temperature, reaction pH, cosubstrate, NAD + , and cell dosage of the biotransformation of 100 mM COBE in this biphasic system were 30 °C, 7.0, mannitol (2.5 mmol/mmol COBE), 0.1 μmol/(mmol COBE), and 0.1 g (wet weight)/mL, respectively. Moreover, COBE at a high concentration of (1,000 mM) could be asymmetrically reduced to ( S )-CHBE in a high yield (99.0 %) and high enantiometric excess value (>99 % ee). Significantly, E. coli CCZU-Y10 shows high potential in the industrial production of ( S )-CHBE (>99 % ee).