Efficient biosynthesis of 3-hydroxypropionic acid in recombinant Escherichia coli by metabolic engineering

Abstract

3-Hydroxypropionic acid (3-HP) is a platform compound that can produce many chemical commodities. This study focuses on establishing and optimizing the production of 3-HP in E. coli. We constructed a series of engineered E. coli strains which can produce 3-HP via the malonyl-CoA pathway. To increase the metabolic flux of acetyl-CoA, a precursor for the synthesis of 3-HP, CRISPR/Cas9-based DNA editing technique was used to knock out the genes encoding pyruvate oxidase (poxB), lactate dehydrogenase (ldhA) and phosphate transacetylase (pta), thereby reducing the formation of by-products. Concurrently, the acetyl coenzyme a carboxylase gene (accDABC) is overexpressed on the chromosome with the objective of augmenting intracellular acetyl-CoA levels and, consequently, 3-HP production. Next, we introduced a plasmid containing a codon-optimized malonyl-CoA reductase gene (mcr) into the engineered strain. Finally, we constructed a transcription factor-based metabolite biosensor utilizing the PpHpdR/PhpdH system, followed by the screening of mutant strains for enhanced 3-HP production through adaptive laboratory evolution. Combining the above metabolic engineering efforts with optimisation of media and fermentation conditions, the 3-HP titer of the engineered strain WY7 increased from an initial titer 0.34 g/L to 48.8 g/L. This study encourages further research in metabolic pathway optimizationto produce 3-HP. HighlightsO_LISynthesis 3-HP in the malonyl-CoA pathway. C_LIO_LIEdit the Escherichia coli genome using the CRISPR/Cas9 system. C_LIO_LIElevated production of 3-HP by knocking out bypass genes ldhA/pta/poxB. C_LIO_LIA biosensor was designed to respond to 3-HP concentration. C_LIO_LIAdaptive laboratory evolutionary strategies increase 3-HP production. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/672340v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1f8b65borg.highwire.dtl.DTLVardef@18c23d6org.highwire.dtl.DTLVardef@184edc3org.highwire.dtl.DTLVardef@15bcc2_HPS_FORMAT_FIGEXP M_FIG C_FIG