Researchers have been encouraged to explore ways of producing foods based on single-cell proteins due to concerns over climate change, animal welfare, and the sustainability issues of rearing meat. Now, Largus Angenent, of the University of Tübingen, and colleagues, have developed a process for producing proteins for human consumption that is sustainable and fits into a circular economy scheme. A renewable protein is the perfect example of how humans can change direction from a fossil-based and wasteful economy to a renewable and closed-loop system.
Angenent said:
It is clear with climate change that we cannot carry on with conventional agriculture.
The method is made possible by a clever two-stage bioprocess that closes nutrient and carbon cycles with renewable electric power. The German scientists designed a biotechnology platform that converts renewable energy and waste resources into edible proteins. They envision the system being scaled up and used to provide food security in the future when the global population reaches ten billion people.
The platform generates yeast biomass that yields a protein mass-fraction of 40–50%.
How It Works
- The two-stage bioprocess employs the bacterium, Clostridium ljungdahlii, in one reactor.
- The bacterium converts carbon dioxide and hydrogen into acetate.
- The conversion is made through the carbon fixing Wood–ljungdahl pathway.
- In a second bioreactor, a pure culture of Saccharomyces cerevisiae (baker’s yeast) with ammonia and oxygen converts the acetate into edible protein suitable for processing into food.
- Renewable energy is used to split water into hydrogen and oxygen.
- Recycled ammonia is used – sourced from industrial waste streams or diluted human urine.
This is not the first microbial protein-generating process. However, those other systems must be fueled by sugar, meaning they still depend on agriculture while Angenent’s method doesn’t. The renewable protein system doesn’t rely on growing crops or fossil fuels, making it the low-carbon footprint that food production desperately needs.
Diana Sousa a microbiology and biotechnology expert at Wageningen University & Research in the Netherlands, says:
This work shows that original yet technically simple alternatives may be the basis to promote circularity in our society. I am thrilled with the prospect of finally seeing the findings of so many scientists working in this field translated into an application that can make an impact for a sustainable society. It builds on years of fundamental research on acetogens – microorganisms that use an ancient pathway to convert carbon dioxide and hydrogen into organic compounds like acids and alcohols.
Willy Verstraete, an expert in microbial resource management from the University of Ghent in Belgium, added:
The proof-of-concept that one can, by this route, nicely produce human food in the form of the common yeast S. cerevisiae, is certainly a step forward and quite a hope for the planet.
Currently, there exists only one commercially available single-cell protein product for human consumption called Quoron.
