Biosynthesis of 4-hydroxybenzylideneacetone by Whole-Cell Escherichia coli

Abstract

4-Hydroxy benzylideneacetone (4-HBA) is an organic synthesis intermediate and can be used as a precursor for the synthesis of raspberry ketone. Herein, 2-deoxy-D-ribose 5-phosphate aldolase (DERA) was overexpressed in E. coli BL21 (DE3) as an attractive catalyst for enzymatic aldol reactions. The aldol reaction between 4-hydroxybenzaldehyde (4-HBD) and acetone to biosynthesize 4-HBA was catalyzed by whole-cell E. coli BL21 (DE3) (pRSF-Deoc). The yield and 4-HBA concentration were 92.8% and 111.35 mM, respectively, when using 120 mM 4-HBD and acetone as substrates. When the concentration of 4-HBD was increased to 480 mM, 376.4 mM 4-HBA was obtained by a fed-batch strategy with a yield of 78.4%, which was about a 28% improvement compared to the one-time addition strategy. E. coli BL21 (DE3) (pRSF-Deoc) cells were further immobilized with K-carrageenan, and the immobilized cells still maintained a residual activity of above 90% after 10 repeated uses. Our study provides a promising method of biosynthesizing 4-HBA.