Polyester and cotton fabrics fill today’s wardrobes. But environmental concerns such as water use and microplastics pollution have revived interest in alternative textiles. In the search for sustainable fabrics, researchers at Pennsylvania State University turned to beer. Or rather the yeast used in its brewing.
The team extracted proteins from spent beer-brewing yeast and spun them into strong textile fibers that avoid the environmental impact of petroleum-based polymers, and the ethical as well as land- and water-use concerns of cotton and wool (Proc. Natl. Acad. Sci. U.S.A. 2025, DOI: 10.1073/pnas.2508931122).
The biobased fibers should fully dissolve in soil and oceans, says Melik Demirel, a materials scientist who led the work. They should also be cost competitive with natural and synthetic fibers when made at large scale. “Sustainability is one aspect, but the price is a much more important aspect,” Demirel says. “If you don’t meet the price metric, [that is] the biggest limitation in . . . entering the market.”
Demirel’s group previously used genetically modified bacteria and yeast to produce proteins found in squid ring teeth and used those to make fibers and other biomaterials. But the process is complex and costly. “In precision fermentation, every condition is set and you are expressing one protein,” he says. In addition, the yeast has to be fed sugar, “which is not cheap at large scale, and you are also tapping into food sources.”
So Demirel and colleagues switched to spent yeast—a by-product of the beer, wine, and pharmaceutical industries—as their protein source. They use a commercial enzyme to break down the yeast walls, then separate the protein pulp from the lipids and sugars and dry it to make a powder.
To make fibers, the researchers borrow a technique that textile companies use today to make the popular biobased polymer lyocell from wood pulp. This involves mixing the protein powder along with cellulose in the solvent N-methyl morpholine N-oxide before extruding the hot solution from a 100 µm-wide spinneret tip into chilled water. Hydrogen bonding between the cellulose and proteins give the fibers their structure and strength. The researchers then twist the fibers into yarn that’s as soft as wool.
Working with a start-up, researchers have spun hundreds of kilograms of fibers from waste yeast proteins, then used the fibers to make yarns. Credit:
Tandem Repeat Technologies
The team’s life-cycle analysis shows that manufacturing yeast protein fibers uses less energy and water than producing wool and polyester. The emission footprint of 5.39 kg of carbon dioxide per kilogram of fiber is slightly higher than polyester, but the biobased material should leave no trace in the environment, according to Demirel. He says that his team is studying the material’s degradation in ocean water but that in soil it should dissolve in a few months, just like squid protein fabrics.
“[This] does not require any purification process or fine-tuning of a specific type of protein, so the process is highly effective and simple for large-scale production,” says Kazuharu Arakawa, who studies spider silk genomics at Keio University. He wonders how the fibers would stand up to repeated washing. “I am also a little bit worried about the possibility of allergy . . . since the material could contain up to 6,000 proteins coded in the yeast genome, and some of them could trigger allergic reaction with sensitive individuals.”
Theanne Schiros, a materials scientist and textile engineer at Columbia University, is curious how the materials perform relative to industry standards for shrinkage and moisture management. Data in the paper show that the fibers are not as strong and flexible as conventional fibers, she says. “However, these differences can be addressed via advances in composition, processing, and textile engineering, such as yarn twist and knit geometries.”
Nonetheless, Arakawa and Schiros agree that the use of fermentation waste to create textiles is exciting. “This is certainly a welcome direction for mankind to shift to sustainable, biodegradable materials,” Arakawa says.
The Penn State team has made 500 kg of fiber at a pilot facility and is scaling up production through Tandem Repeat Technologies, a start-up that Demirel originally cofounded to commercialize his squid protein fibers. The company has partnerships with major US and European brands, he says, and the material’s cost should become competitive with wool and even cotton with increased production.
Prachi Patel is a senior editor and physical sciences reporter at C&EN based in Pittsburgh.
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