Scientists invent a way to create and dye rainbow-colored fabric in the lab using E. coli

Scientists used genetically modified bacteria to simultaneously create and color fabric in a one-pot method. Compared to current methods that rely on fossil fuels, this new technology provides a simpler and more sustainable way to produce colored fabrics.

In a new study published Nov. 12 in the journal Trends in Biotechnology, researchers created cellulose-based fabrics that span the colors of the rainbow by varying the conditions used to grow bacteria.

Synthetic fibers “are highly dependent on chemical synthesis and post-processing steps, which are energy-intensive, labor-intensive, and harmful to the environment,” said study lead author Sang Yeop Lee, a professor in the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology. Such processes can emit large amounts of greenhouse gases and contaminate water and soil with heavy metals and carcinogens, Lee told LiveScience in an email.

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Therefore, in recent years there has been a growing trend to use alternative methods of producing natural fibers from bacterial fermentation. Cellulose is a promising target because it is a material that mimics the natural fibers found in textiles such as cotton. Typically, various bacteria convert glucose into cellulose fibers to provide structural support and protection from other microorganisms. However, cellulose produced by bacteria is naturally white and often needs to be dyed after processing.

Lee and his team have now simplified this process by growing cellulose-producing bacteria alongside microbes that produce natural colorants. The research team created two classes of pigments using color-producing strains of Escherichia coli (E. coli). One is the dark violacein (which produces colors such as purple, blue, and green) and the other is the warm carotenoid (which produces colors such as red, orange, and yellow).

First, the researchers genetically modified the metabolic pathway of a strain of Komagataeibacter xylinus bacteria to increase cellulose production during fermentation. Violacein-producing E. coli was then added to the reaction vessel, resulting in fabrics dyed purple, blue, and green.

However, the team was unable to achieve warm tones using the same method because the bacteria did not produce enough dye to dye the cellulose fabric, probably due to insufficient bacterial growth. To overcome this problem, they added pre-grown and treated cellulose to cultures of carotenoid-producing E. coli. Using this co-culture method, they were able to dye the fabric red, orange and yellow, completing the team’s iridescent palette.

Overall, the method “eliminates the need for separate dyeing and cleaning processes,” Lee said, adding that this helps reduce chemical waste and water consumption.

The colored bacterial cellulose showed overall strong stability against acids, bases, heat treatments, and washing. However, the team noted that further work is needed to fully test these materials, particularly to confirm their resistance to industrial detergents and mechanical abrasion.

Going forward, Lee hopes to “expand the current seven-color platform more broadly” and scale up the process to an industrial level while maintaining consistent quality. Further changes in the way bacteria produce cellulose could open up other uses for the material, such as biodegradable packaging, he said.