Reducing Cooling Costs for Sustainable Food Biomanufacturing With Thermotolerant Cupriavidus necator H16 Mutant

Autotrophic CO₂ conversion to Single Cell Protein (SCP) using H₂ and O₂ is gaining commercial traction for food and feed production. Cupriavidus necator H16 is a key chassis organism for this "knallgas" fermentation, but industrial operation is typically constrained to ~30°C due to poor autotrophic growth at higher temperatures. Autotrophic growth at 37°C would enable the use of low-cost cooling water instead of chilled water, offering substantial reduction in cooling expenses. Here, we characterised a spontaneous C. necator mutant that conferred 37°C-thermotolerance when grown autotrophically, and compared its performance to the wild type. In batch cultures at 30°C, both strains showed comparable growth. At 37°C, only the spontaneous mutant grew autotrophically, albeit with a lower maximum growth rate than at 30°C. In chemostat cultivations no clear phycological differences could be resolved within the experimental uncertainty relative to the wild type at 30°C, in terms of PHB production, CO₂ uptake at 37°C, and proteinogenic amino acid composition. Techno-economic modelling of a 160 kt a^-1 SCP process indicated that operation at 37°C can reduce cooling utility costs up to 75%, saving ~US$ 0.98 per kg SCP (20%-50% of the production costs). Operating at 37°C with thermotolerant strains could subsequently decrease production costs substantially, making CO₂-derived SCP production more economically viable at scale.