Microbes make nutrients out of thin air; richer source of protein than beef, fish

Scientists in Germany have developed a method to obtain protein and vitamin B9 from microbes by providing them with little more than hydrogen, oxygen, and carbon dioxide.

Powered by renewable energy, this technology produces a sustainable, nutrient-rich protein substitute that could eventually become a part of our daily diets.

“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 author Largus Angenent of the University of Tübingen, Germany.

“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.”

Yeast, hydrogen, carbon dioxide: A winning combo

The researchers developed a bioreactor system with two stages that creates protein- and vitamin B9-rich yeast. In the first stage, a bacterium called Thermoanaerobacter kivui converts hydrogen and carbon dioxide into acetate, a compound also found in vinegar.

In the second stage, Saccharomyces cerevisiae (commonly known as baker’s yeast) consumes the acetate and oxygen to generate both protein and vitamin B9. The hydrogen and oxygen needed for this process can be obtained by splitting water using electricity from renewable sources like wind energy.

Interestingly, yeast fed with acetate produces roughly the same amount of vitamin B9 as yeast that relies on sugar. A small portion—just 6 grams or 0.4 tablespoons of dried yeast—provides enough vitamin B9 to meet the daily recommended intake.

“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 Angenent.

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

Surpassing animal-derived protein

The researchers discovered that the protein content in their yeast surpasses that of common sources like beef, pork, fish, and lentils. A serving of 85 grams, or about 6 tablespoons, provides 61% of daily protein needs. In comparison, beef supplies 34%, pork 25%, and both fish and lentils provide 38%.

However, before consumption, the yeast needs treatment to remove compounds that could raise the risk of gout if eaten in large amounts. Even after treatment, the yeast still delivers 41% of the daily protein requirement, making it a competitive alternative to traditional protein sources.

This innovative technology tackles critical global issues such as environmental sustainability, food security, and public health. The system significantly reduces carbon emissions associated with food production by using renewable energy and carbon dioxide.

It also breaks the dependence on land for farming, creating opportunities for land conservation. The lead researcher, Angenent, emphasizes that the goal isn’t to replace farmers but to encourage the sustainable production of vegetables and crops. The team’s yeast could also be a valuable tool in combating food shortages and nutrient deficiencies, particularly in developing countries.

Next steps

However, before you can expect to see the team’s yeast on grocery shelves as a protein alternative, lead researcher Angenent notes that there’s still significant work ahead. The team plans to refine and expand production, ensure food safety, perform technical and economic evaluations, and assess consumer demand in the marketplace.

“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 study has been published in Cell Press’s journal Trends in Biotechnology .