The linchpin for this technology is Xanthobacter species. Solar Foods co-founders — energy systems researcher Pasi Vainikka, Solar CEO; bioprocess engineer Juha-Pekka Pitkänen, CTO; and collaborators — discovered it on a Baltic beach during a soil expedition around Finland. Known as autotrophic hydrogen-oxidizing bacteria, these microbes synthesize their own food by capturing the mixture of gases — oxygen, nitrogen, CO2 and water vapor — in atmospheric air. The scientists apply electricity, which splits water into hydrogen and oxygen, and because these autotrophs contain hydrogenases that use hydrogen as an electron donor, they can fix CO2. Overall, these reactions transform inorganic gases into organic compounds that serve as nutrients. Thus, the microbes grow in bioreactors fed by air; once they are harvested and dried, the resulting biomass consists of 65–70% protein, 5–8% fat, 10–15% dietary fiber and 3–5% mineral nutrients. Solar has requested approval from the European Food Safety Authority of the resulting protein product, which they call Solein.
“Microbial protein production using hydrogen-oxidizing bacteria is not new and dates back to 1964,” says Pitkänen. “We just brought clean energy to capture carbon and turn electricity into edible calories.” These edible ingredients can be produced using minimal land use (except for the factory) and one-tenth of the water used by soybean production, claims Solar Foods, and the bacteria can grow in the dark in ordinary bioreactors using hydrogen as the energy source.
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