Prospects for engineering Ralstonia eutropha and Zymomonas mobilis for the autotrophic production of 2,3-butanediol from CO2 and H2

Abstract

The decarbonization of the chemical industry and a shift toward circular economies because of high global CO₂ emissions make CO₂ an attractive feedstock for manufacturing chemicals. Moreover, H₂ is a low-cost and carbon-free reductant because technologies such as solar-driven electrolysis and supercritical water (scH₂O) gasification enable sustainable production of molecular hydrogen (H₂). We review the recent advances in engineering Ralstonia eutropha, the representative species of “Knallgas” bacteria, for utilizing CO₂ and H₂ to autotrophically produce 2,3-butanediol (2,3-BDO). This assessment is focused on state-of-the-art approaches for splitting H₂ to supply energy in the form of ATP and NADH to power cellular reactions and employing the Calvin-Benson-Bassham cycle for CO₂ fixation. Major challenges and opportunities for application and future perspectives are discussed in the context of developing other promising CO₂ and H₂-utilizing microorganisms, exemplified by Zymomonas mobilis.