Biotechnology Letters, Vol.37, No.6, 1233-1241, 2015
Enhancement of phenyllactic acid biosynthesis by recognition site replacement of D-lactate dehydrogenase from Lactobacillus pentosus
The Tyr52 residue of d-lactate dehydrogenase (d-LDH) from Lactobacillus pentosus was replaced with small hydrophobic residues and overexpressed in E. coli BL21 (DE3) to enhance 3-phenyllactic acid (PLA) synthesis by whole-cell catalyst. Escherichia coli pET-28a-d-ldh produced 12.2 g PLA l(-1) in 3 h, with a molar conversion rate of 61 %, while E. coli pET-28a-d-ldh (Y52V) produced 15.6 g PLA l(-1), with a molar conversion rate of 77 %. This study demonstrates the feasibility of using engineered E. coli for PLA production from phenylpyruvate (PPA) and showed that site-directed mutagenesis of d-ldh markedly improved PLA yield and substrate conversion rate. This biocatalytic system is a promising platform for PLA production from PPA.
Keywords:D-Lactate dehydrogenase;3-Phenyllactic acid;Phenylpyruvic acid;Recognition site residue replacement;Whole-cell transformation