Biosynthesis of (R)-3-hydroxybutyric acid from syngas-derived acetate in engineered Escherichia coli

Acetate is a potential non-food carbon source for industrial production, coping with the shortage of food-based feedstocks. (R)-3-hydroxybutyric acid (R-3HB) can be used as an important chiral intermediate in the fine chemical and pharmaceutical industry. In this study, the R-3HB biosynthesis pathway was successfully constructed when genes of β-ketothiolase (phaA), acetoacetyl-CoA reductase (phaB) from Ralstonia eutropha, and propionyl-CoA transferases (pct) from Clostridium beijerinckii 8052 were introducedinto Escherichia coli. The effects of host E. coli strains, different propionyl-CoA transferases, and post-induction temperatures were investigated. The final concentration of R-3HB reached 0.86 g/L using acetate as the sole carbon source. Subsequently, a kind of culture broth containing the syngas-derived acetate was used to produce 1.02 g/L of R-3HB with a yield of 0.26 g/g. Inthis study, the engineered E. coli strain could efficiently utilize syngas-derived acetate to synthesize R-3HB.