German Researchers Develop Sustainable Protein Source from Bacteria

German researchers have developed a method to extract protein and vitamin B9 from bacteria using only CO₂, hydrogen, and oxygen. This process, powered by renewable energy, produces a sustainable, micronutrient-rich protein substitute that could eventually make its way into our food supply. The study was published on September 12th, 2024, in the Cell Press journal Trends in Biotechnology.

This is a fermentation process similar to how you make beer, but instead of giving the microbes sugar, we gave them gas and acetate. 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.

Largus T. Angenent, Study Corresponding Author and Professor, University of Tübingen

Angenent added, “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. One alternative is growing proteins in bioreactors through biotechnology rather than growing crops to feed animals. It makes agriculture much more efficient.”

The researchers developed a two-stage bioreactor system to produce yeast rich in protein and vitamin B9, commonly known as folate, which is essential for cell growth and metabolism. In the first stage, the bacterium Thermoanaerobacter kivui converts hydrogen and CO₂ into acetate, a compound found in vinegar.

In the second stage, Saccharomyces cerevisiae, or baker's yeast, uses acetate and oxygen to produce protein and vitamin B9. Hydrogen and oxygen can be generated by splitting water with electricity from renewable energy sources like windmills.

Interestingly, yeast grown on acetate produces almost the same amount of vitamin B9 as yeast grown on sugar. Just 6 grams (0.4 tablespoon) of dried yeast meets the daily vitamin B9 requirement. A team from the Technical University of Munich, led by co-author Michael Rychlik, confirmed the vitamin levels.

The study also revealed that the yeast contains more protein than beef, pork, fish, or lentils. Consuming 85 grams (about six tablespoons) of the yeast provides 61% of daily protein needs, while beef, pork, fish, and lentils contribute 34 %, 25 %, 38 %, and 38 %, respectively.

However, the yeast must be processed to remove certain components that, if consumed in excess, could increase the risk of gout. Even after processing, the yeast still provides 41 % of the daily protein requirement, comparable to traditional protein sources.

This technology addresses several global challenges, including environmental conservation, food security, and public health. Powered by sustainable energy and CO₂, it reduces carbon emissions associated with food production and frees up land for conservation by separating food production from traditional farming.

Angenent emphasizes that this technology is not meant to outcompete farmers. Instead, it will allow them to focus on sustainably growing vegetables and other crops. The yeast could also help combat food scarcity and nutritional deficiencies in impoverished regions by providing a reliable source of protein and vitamin B9.

While promising, Angenent notes that more work is needed before this yeast becomes available as a protein substitute at grocery stores. Future steps include ensuring food safety, conducting technical and economic assessments, understanding consumer demand, and optimizing and scaling up production.

Angenent concluded, “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. The end product is vegetarian/vegan, non-GMO, and sustainable, which could appeal to consumers.”

Alexander von Humboldt Foundation, the Federal Ministry of Education and Research in Germany, the Novo Nordisk Foundation CO₂ Research Center (CORC), SPRIND GmbH, and the Federal Ministry of Education and Research supported the study.

Journal Reference:

Angenent, T., L., et al. (2024) Powered by renewable energy, microbes turn CO₂ into protein and vitamins. Trends in Biotechnology. doi.org/10.1016/j.tibtech.2024.06.014