Sequential pretreatment of bamboo shoot shell and biosynthesis of ethyl (R)-4-chloro-3-hydroxybutanoate in aqueous-butyl acetate media

Abstract

Abstract Organic solvent of low log P value could be used to remove hemicellulose and lignin in bamboo shoot shell (BSS). Combination pretreatment with biocompatible butyl acetate (Log P = 1.7, 10 v%) and dilute sodium acetate (NaAc, 2 wt%) was chosen to pretreat BSS by autoclaving (110 °C, 40 min, pretreatment severity factor Log R0 = 3.2) for enhancing enzymatic in situ saccharification of BSS. In the BSS-hydrolysates, soluble sugars (500 mM glucose, 419.3 mM xylose, 29.9 mM cellobiose and 129.4 mM arabinose) significantly increased the intracellular NADH content and the biocatalytic activity of recombinant E. coli CCZU-H15 whole-cells when 500 mM ethyl 4-chloro-3-oxobutanoate (COBE) were biologically converted. Ethyl (R)-4-chloro-3-hydroxybutanoate [(R)-CHBE] was obtained at 98.5% yield without extra addition of cofactor. In summary, this strategy involving combination pretreatment, enzymatic hydrolysis without washing/detoxification, and bioreduction of COBE has high potential application for the effective biosynthesis of (R)-CHBE.