Effective biosynthesis of ethyl (R)-4-chloro-3-hydroxybutanoate by supplementation of l-glutamine, d-xylose and β-cyclodextrin in n-butyl acetate-water media.

•l-Glutamine and d-xylose were used to enhance the reductase activity.•β-Cyclodextrin was used to produce ethyl (R)-4-chloro-3-hydroxybutanoate.•Ethyl 4-chloro-3-oxobutanoate (800mM) was effectively biotransformed.•Ethyl (R)-4-chloro-3-hydroxybutanoate (>99% ee) was obtained at 100% yield.