In the future, our clothing could come from vats of live microbes. Because certain bacteria can produce textile fibers, others can dye these fibers in all colors of the rainbow. If you put both microbial species in the same bioreactor, you get colored textile fibers from which clothing can then be woven and sewn. This newly developed production approach offers a sustainable alternative to current practices in the chemical-intensive textile industry.
The textile industry produces enormous quantities of clothing every day from a wide variety of materials and in a wide variety of colors. Raw materials are used that are not very sustainable, are often harmful to the environment and health, or even toxic. “The industry relies on petroleum-based synthetic fibers and chemicals for dyeing, which include carcinogens, heavy metals and endocrine disruptors,” explains senior author San Yup Lee of the Korea Advanced Institute of Science and Technology (KAIST). “These processes produce a lot of greenhouse gases, degrade water quality and pollute the soil.” In addition, the pollutants released interfere with the metabolism of plants, animals and people.
Researchers have therefore been looking for “green” alternatives for textile production for a long time. For example, petroleum-based fibers such as polyester and nylon can be replaced with bacterial cellulose. These sustainable, mostly white fibers are produced by genetically optimized microbes via fermentation and are well suited as a substitute raw material, as several tests in recent years have shown. However, it has been a challenge to make the dyeing processes in the textile industry more environmentally friendly and also to dye biocellulose.
Colored cellulose fibers from a “pot”
A team led by Lee and first author Hengrui Zhou from KAIST has now developed a new technique to dye textile fibers with natural pigments. To do this, they bred bacteria of the species Komagataeibacter xylinus, which use their metabolism to spin cellulose threads in large quantities, as well as Escherichia coli bacteria, which produce abundant natural dyes. The latter can produce different color molecules depending on the gene variant introduced: violaceins, which produce cool colors from green to violet, and carotenoids, which produce warm colors from red to yellow. The special thing about Zhou and his colleagues’ approach: They tried to cultivate both types of bacteria at the same time, thus enabling fiber synthesis and coloring in parallel. “At first, our breeding attempt was a complete failure. Either the cellulose production was much lower than expected or it didn’t change color,” reports Lee. The reason: The two types of bacteria interfered with each other’s growth.
The researchers then optimized their recipe, but they were not entirely successful in allowing both microbial species to grow peacefully next to each other. Instead, they found a partial solution: To create fibers colored with the cool violaceins, they first let the cellulose bacteria grow alone, giving them a head start. They then added the dye-producing bacteria after a delay. In this delayed co-culture approach, each bacterium was able to do its job without disturbing the other, the experiments show. However, this approach did not work with warm-toned carotenoids. The team therefore developed another method. The cellulose bacteria are also initially cultivated alone. The cellulose produced in this way is then harvested and cleaned of the cellulose bacteria before the pigment-producing bacteria are added. In this sequential approach, both types of microbes grow completely separately and one after the other.
How good is the colorful biocellulose?
Taken together, these two strategies can produce a colorful range of cellulosic fabrics in purple, navy, blue, green, yellow, orange and red. Further tests showed that most of these seven colors are also robust and remain in the fibers despite subsequent stress – for example when they come into contact with heat, water, soap, bleach, acid or alkali, which can occur in our everyday clothing. The luminosity of the cellulose fibers dyed with violaceins was even more stable in the washing tests than that of fibers with synthetic dyes.
A key advantage of the new production method is that only bacteria and natural and renewable ingredients are required. Chemicals that are harmful to the environment or health are not used. In the long term, the process is therefore suitable for more sustainable clothing production. “Our work will not change the entire textile industry at the moment. But at least we have proposed an environmentally friendly path towards sustainable textile dyeing while producing cellulose,” says Lee.
The team estimates that it will take at least five years before the bacteria-based substances reach the shelves. The colorful eco-fibers are still too expensive and can only be produced on a small scale. In order to change that, the process must now be further optimized. Other colors should also come into play. However, the researchers also appeal to buyers to place more value on the sustainability of their clothing in the future than on the price. This would make the transition to an environmentally friendly textile industry easier. “Let’s do something good for future generations,” says Lee.
Source: Hengrui Zhou (Korea Advanced Institute of Science and Technology) et al.; trends in biotechnology, doi: 10.1016/j.tibtech.2025.09.019