Multilayer Engineering of an Escherichia coli-Based Biotransformation System to Exclusively Produce Glycolic Acid from Formaldehyde

A whole-cell biocatalysis was investigated for the selective synthesis of the industrially relevant C2 chemicals (e.g., glycolic acid (3)) from formaldehyde (1). Escherichia coli cells were engineered to overexpress a carboligase and an aldehyde dehydrogenase from E. coli K-12. Moreover, the side reactions, which dissipate formaldehyde and glycolic acid, were removed to produce glycolic acid to a high conversion. Host cell engineering to apply relatively chemical tolerant E. coli strains as well as substrate engineering to avoid the toxic effects of formaldehyde to the host cells allowed production of glycolic acid up to 27 mM in the reaction medium with a conversion of 85%. This study will contribute to valorization of C1 gas (e.g., CH₄, CO₂, and CO) to industrially relevant C2 chemicals in a sustainable way.