Powered by renewable energy, microbes transform CO₂ into proteins and vitamins

German researchers manage to extract proteins and vitamin B9 from microbes by feeding them only hydrogen, oxygen and CO₂. The technology, published September 12 in the journal Trends in biotechnologyruns on renewable energy to produce a sustainable, micronutrient-enriched protein alternative that could one day make it onto our plates.

“This is a fermentation process similar to that of beer making, but instead of giving the microbes sugar, we gave them gas and acetate,” says corresponding author Largus Angenent of the University of Tübingen, Germany. “We knew that yeast could produce vitamin B9 themselves from sugar, but we didn’t know if they could do the same with acetate.”

“We are approaching 10 billion people on the planet and, with climate change and limited land resources, producing enough food will become increasingly difficult,” Angenent says. “One alternative is to grow proteins in bioreactors using biotechnology rather than growing plants to feed animals. This makes agriculture much more efficient.”

The team designed a two-stage bioreactor system that produces yeast rich in protein and vitamin B9. This vitamin is also known as folate and is essential for bodily functions such as cell growth and metabolism. In the first stage, the bacteria Thermoanaerobacter kivui converts hydrogen and CO₂ acetate, which is found in vinegar.

In the second stage, Saccharomyces cerevisiae, better known as baker’s yeast, feeds on acetate and oxygen to make proteins and vitamin B9. Hydrogen and oxygen can be produced by absorbing water with electricity generated by clean energy sources such as wind turbines, for example.

It turns out that yeast fed acetate produced about the same amount of vitamin B9 as those fed sugar. Just 6 grams, or 0.4 tablespoons, of harvested dried yeast met the daily requirement for vitamin B9. The vitamin levels were measured by a team led by co-author Michael Rychlik of the Technical University of Munich in Germany.

When it comes to protein, the researchers found that yeast levels in their diet exceeded those of beef, pork, fish, and lentils. Eighty-five grams, or 6 tablespoons, of yeast provides 61 percent of daily protein needs, while beef, pork, fish, and lentils provide 34 percent, 25 percent, 38 percent, and 38 percent of needs, respectively.

However, yeast must be processed to remove compounds that can increase the risk of gout if consumed in excess. Despite this, processed yeast still provides 41% of daily protein needs, which is comparable to traditional protein sources.

This technology aims to address several global challenges: environmental preservation, food security and public health. Powered by clean energy and CO₂The system reduces carbon emissions in food production. It decouples land use from agriculture, freeing up space for conservation.

Angenent also emphasizes that this technology will not compete with farmers. Instead, it will help them focus on producing sustainable vegetables and crops. The yeast developed by the team could also help developing countries overcome food shortages and nutritional deficiencies by providing them with protein and vitamin B9.

But before the research team’s yeast can be purchased on a grocery aisle as a protein alternative, Angenent says there’s still a lot to do. They plan to optimize and scale up production, study food safety, conduct technical and economic analyses, and assess market interest.

“The fact that we can produce vitamins and proteins at the same time at a fairly high production rate without using land is exciting,” Angenent says. “The end product is vegetarian/vegan, GMO-free and sustainable, which could appeal to consumers.”