Imma Perfetto
Cosmos science journalist
German researchers have farmed yeast rich in protein and vitamin B9 (folate) by feeding them hydrogen, oxygen, and carbon dioxide.
Protein levels in the harvested dried yeast is similar to that of beef, pork, fish, and lentils, and just 6 grams, or 0.4 tablespoon, provides the recommended daily folate requirement.
The proof-of-concept system, which runs on renewable energy, aims to offer a sustainable protein alternative to conventional agriculture.
“We are approaching 10 billion people in the world, and with climate change and limited land resources, producing enough food will become harder and harder,” says Largus Angenent of the University of Tübingen, Germany, corresponding author of the paper in Trends in Biotechnology.
“One alternative is growing proteins in bioreactors through biotechnology rather than growing crops to feed animals. It makes agriculture much more efficient.
The system involves a 2-stage bioreactor. In the first stage, a bacterium, Thermoanaerobacter kivui, converts CO2 and H2 into acetate, the salt of acetic acid (vinegar).
In the second stage, baker’s yeast (Saccharomyces cerevisiae) grown in a medium with necessary vitamins, produces protein and vitamin B9 by feeding on the acetate and O2.
The researchers say the hydrogen and oxygen could be produced through the splitting of water molecules (hydrolysis) using electricity powered by renewable energy.
“This is a fermentation process similar to how you make beer, but instead of giving the microbes sugar, we gave them gas and acetate,” says Angenent.
“We knew that yeast could produce vitamin B9 on their own with sugar, however, we didn’t know if they could do the same with acetate.”
Once the resulting dried yeast was treated to remove nucleic acids (which can increase the risk of gout when consumed at high levels), they found that just 85g, or 6 tablespoons, provided 41% of a person’s daily protein needs. This is comparable to the same serving of beef, pork, fish, and lentils, which contain 34%, 25%, 38%, and 38%, respectively.
“The fact that we can make vitamins and protein at the same time at a pretty high production rate without using any land is exciting,” says Angenent.
“The end product is vegetarian/vegan, non-GMO, and sustainable, which could appeal to consumers.”
The researchers have shown the yeast is feasible to produce at the laboratory scale, but more research is needed to optimise and scale up production, investigate food safety, and conduct technical and economic analyses, before a product finally reaches grocery stores.
