One stone two birds: Biosynthesis of 3-hydroxypropionic acid from CO2 and syngas-derived acetic acid in Escherichia coli

Syngas,which contains large amount of CO2 as well as H2 and CO,can be convert to acetic acid chemically or biologically.Nowadays,acetic acid become a cost-effective nonfood-based carbon source for value-added biochemical production.In this study,acetic acid and CO2 were used as substrates for the biosynthesis of 3-hydroxypropionic acid(3-HP)in metabolically engineered Escherichia coli carrying heterogeneous acetyl-CoA carboxylase(Acc)from Corynebacterium glutamicum and codon-optimized malonyl-CoA reductase(MCR)from Chloroflexus aurantiacus.Strategies of metabolic engineering included promoting glyoxylate shunt pathway,inhibiting fatty acid synthesis,dynamic regulating of TCA cycle,and enhancing the assimilation of acetic acid.The engineered strain LNY07(M*DA)accumulated 15.8 g/L of 3-HP with the yield of 0.71 g/g in 48 h by whole-cell biocatalysis.Then,syngas-derived acetic acid was used as substrate instead of pure acetic acid.The concentration of 3-HP reached 11.2 g/L with the yield of 0.55 g/g in LNY07(M*DA).The results could potentially contribute to the future development of an industrial bioprocess of 3-HP production from syngas-derived acetic acid.