Biosurfactants that are produced by the fermentation of sugar are in demand for the manufacture of cosmetics and detergents.
Five years ago, the laboratory’s first attempts to produce biosurfactants by means of fermentation created huge mounds of foam, recalls Dr. Hans Henning Wenk, the head of Research and Development at Evonik Care Solutions. However, the experts in Slovenská Ľupča (Slovakia) now have the process firmly under control, and are using rhamnolipids produced by bacteria to manufacture biosurfactants.
Surfactants are contained in dishwashing detergents, shower gels, and bath additives, where they ensure that dirt doesn’t collect again on dishes or skin. In the European Union, surfactants have to largely break down during wastewater treatment, which is why the consumer goods industry is increasingly using biosurfactants. However, the demand is also growing in regions where sewage treatment plants are rare but people are becoming increasingly environmentally conscious.
After its start in the cosmetics sector, Evonik and its partner Unilever developed a hand dishwashing liquid based on such biosurfactants. The product is already on the market in Chile and Vietnam, where dishes are generally washed by hand. Thanks to rhamnolipids, hand dishwashing liquids that are based on biosurfactants are on a par with very good products based on synthetic surfactants. The demand for these sustainable raw materials is rapidly increasing. For example, Unilever wants to stop using fossil carbon in its household and textile care formulations by 2030. Rhamnolipids are now also found in toothpaste, facial cleansers, and shampoos. Evonik is therefore continuing to invest in this production technique in order to strengthen its leading position in this globally growing market.
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DOWN THE DRAIN
The biosurfactants that Evonik produces consist of a sugar component and a fatty acid component. For the fermentation process, the company uses a strain of bacteria that produces both components from plant-based sugars. Evonik uses dextrose as a substrate, which is made from plants such as European corn. Not only are the raw materials and the production process environmentally friendly, the product itself also has a low environmental impact. Says Wenk: “In the end, it goes down the drain and to the sewage treatment plant. In some regions, it is even released directly into the environment.” However, the environmental impact is vastly reduced because rhamnolipids are much less toxic than conventional surfactants and very easily biodegradable.
The main feature of Evonik’s fermentation process is its scalability. Although many natural bacteria convert fats into rhamnolipids, they only do so in microscopic amounts. At Evonik, this task is performed by Pseudomonas putida, a well-researched “safety strain.” “After we gave it the genetic tools to produce rhamnolipids in large amounts, we continuously optimized it further,” says Wenk.
The process ultimately created a strain of bacteria that produces biosurfactants in industrial amounts. “To achieve this, we got bioengineers together with process experts, chemists, and engineers,” reports Wenk. “We benefited here from our experience with the development of surfactants.” The expertise of a physical chemist proved to be crucial because he was able to explain why a surfactant that had some of its parameters modified suddenly behaved completely differently than before. This knowledge enabled the researchers to get the foam under control so that it now only goes into action in sinks and bathtubs.