Sustainable D/L-Lactate Production from Methane and Carbon Dioxide via Acetylenedicarboxylate

Lactic acid (LA), a high-value chemical with extensive applications, is currently produced either from petrochemical sources, which are economically unviable or through fermentation of sugars with laborious pretreatment steps. We present acetylenedicarboxylate (ADCA), obtained from methane and carbon dioxide through commercial processes, as an alternative feedstock for LA production. In this study, we developed both in vitro and in vivo enzymatic routes for converting ADCA to LA employing FumA, MaeB, and LDH. We achieved LA yields of 0.96 mol/mol and 0.61 mol/mol for in vitro and in vivo approaches, respectively. We observed the complete conversion of 25 mM ADCA to lactate within 30 minutes, with 0.1 units of each enzyme. The in vivo approach involved using ALE isolates, strains harboring deletions in dcuC, and a fumA knockout mutant as a plasmid addiction strategy. These findings demonstrate the feasibility of using ADCA as a sustainable feedstock for LA production, offering a promising alternative for the production of commodity chemicals.