Strain and model development for auto- and heterotrophic 2,3-butanediol production using Cupriavidus necator H16

The production of platform chemicals from renewable energy sources is a crucial step towards a post-fossil economy. This study reports on the production of acetoin and 2,3-butanediol heterotrophically with fructose as substrate and autotrophically from CO₂ as carbon source, H₂ as electron donor and O₂ as electron acceptor with Cupriavidus necator. In a previous study, the strain was developed for the production of acetoin with high carbon efficiency. Acetoin can serve as a precursor for the synthesis of 2,3-butanediol by the integration of a butanediol dehydrogenase. In this study, different plasmid backbones and butanediol dehydrogenases were evaluated regarding efficiency for CO₂-based 2,3-butanediol production. The developed strain utilizes the pBBR1 plasmid bearing a 2,3-butanediol dehydrogenase from Enterobacter cloacae and is characterized by 2,3-butanediol as the main product and a heterotrophic total product yield of 88.11%, an autotrophic volumetric productivity of 39.45 mg L^-1 h^-1, a total product carbon yield of 81.6%, an H₂ efficiency of 33.46%, and a specific productivity of 0.016 g product per gram of biomass per hour. In addition, a mathematical model was developed to simulate the processes under these conditions. With this model, it was possible to calculate productivities and substrate usage at distinct time points of the production processes and calculate productivities and substrate usage with high resolution which will be useful in future applications.