Food from CO2 and Formate: C1 feedstocks as fuels for novel food production

While the world’s population is rapidly increasing, climate change is threatening traditional agriculture and decreasing global food security. Bacteria may use CO2 and hydrogen gas as the sole carbon and energy sources, respectively, to produce single-cell protein - a microbial biomass-based food source. Alternatively, CO2 can be converted to formate, which bacteria may convert into single-cell protein without the need for hydrogen gas. However, CO2 fermentation scale-up is hindered by low gas solubilities and the safety concerns related to hydrogen’s explosive nature, while formate fermentations lack scalability due to slow and inefficient microorganism growth on this substrate. This project aims to develop a scalable single-cell protein production process from CO2 or CO2-based formate, with the latter substrate being the primary focus to date. So far, microorganisms with potential for scale-up have been screened, with efforts made at optimising their ability to convert formate into single-cell protein. For optimisation, lab-scale fermentations coupled with mathematical growth modelling are employed, highlighting the individual influence of formate concentration, pH, and buffering capacity on growth rates and biomass yields, as well as a dynamic interaction between the three factors. Additionally, co-feeding formate with pot ale, a low-cost distillery by-product, may benefit the fermentation, showcasing how distillery by-products can help to maximise CO2 valorisation. With further fermentation strategy optimisation, CO2-based formate may be a viable feedstock for sustainable food production at scale.