Isopropanol production from carbon dioxide in Cupriavidus necator in a pressurized bioreactor.

A bioreactor was designed to provide high gas mass transfer to reach cell and product titres in the g L level from CO for realistic, laboratory scale, engineered autotrophic strain evaluation. The design was based on independent CO, H and air inputs and the ability to operate at high pressures. The bioreactor configuration and cultivation strategy enabled growth of Cupriavidus necator strains for long periods, to reach over 3 g L dry cell weight. No negative impact of the high pressure was observed on viability of the strains up to more than 4 bar overpressure. The cultivation was then carried out using an engineered isopropanol producing strain; in this case, 3.5 g L isopropanol was obtained from CO as the sole carbon source. This is the first reported demonstration of a successful production from engineered bacteria of product in the g L range on CO, raising the prospect of future development of CO-based bioprocesses.