Cupriavidus necator as a model organism for CO2-based biotechnology

Abstract

Cupriavidus necator H16 is a chemolithoautotrophic model organism that can grow in a simple mineral medium supplemented with the gases H₂, O₂ and CO₂. This unique metabolic capability makes it a promising organism for sustainable biotechnology applications such as the production of bioplastics, single cell proteins and bulk chemicals from renewable resources. However, gas fermentation, particularly with explosive gas mixtures like H₂ and O₂, poses considerable technical and safety challenges. Effective control of gas mixtures, pressurized environments, mass transfer from gas to liquid and gas solubility is essential to ensure both reproducibility and safety in bioprocessing systems. This chapter describes a detailed methodology for the cultivation of C. necator across various micro, small- and medium-scale setups, while emphasizing safety protocols. The chapter also outlines analytical techniques for the quantification of polyhydroxybutyrate (PHB), single cell protein and isopropanol as product examples for gas fermentation.

Keywords: Biosynthesis; Bulk chemicals; Carbon dioxide; Cupriavidus necator; Gas fermentation; Molecular hydrogen; Polyhydroxybutyrate (PHB); Single cell protein.