Blending industrial blast furnace gas with H2 enables Acetobacterium woodii to efficiently co-utilize CO, CO2 and H2

Abstract

In this study, the impact of gas composition (i.e. CO, CO₂ and H₂ partial pressures) on CO₂ utilization, growth, and acetate production was investigated in batch and continuous cultures of A. woodii. Based on an industrial blast furnace gas, H₂ blending was used to study the impact of H₂ availability on CO₂ fixation alone and together with CO using idealized gas streams. With H₂ available as an additional energy source, net CO₂ fixation and CO, CO₂ and H₂ co-utilization was achieved in gas-limited fermentations. Using industrial blast furnace gas, up to 15.1 g l^-1 acetate were produced in continuous cultures. Flux balance analysis showed that intracellular fluxes and total ATP production were dependent on the availability of H₂ and CO. Overall, H₂ blending was shown to be a suitable control strategy for gas fermentations and demonstrated that A. woodii is an interesting host for CO₂ fixation from industrial gas streams.

Keywords: Acetogens; Industrial CO(2) emissions; Maximum specific hydrogen uptake rate; Mixed gas fermentation; Net CO(2) fixation.