Producing everyday products with fungi2 November 2018

Laboratory-scale bioreactor for optimizing fermentationconditions. Credit: Fraunhofer-Gesellschaft

Most detergents, cosmetics, and clothes, to namejust a few products, are manufactured usingpetroleum, making such everyday items anythingbut eco-friendly. It is now possible to produce thebio-based and CO2-neutral basic chemicals forsuch articles with the help of fungi. Fraunhoferresearch teams are developing fermentationtechniques and manufacturing processes toproduce them on an industrial scale.

If you find a layer of blue-green mold covering yourbread, fruit or something else from your pantry,you'll quite rightly end up throwing it out with thegarbage – fungi are after all harmful to your health.Researchers at the Fraunhofer Institute forInterfacial Engineering and Biotechnology IGB inStuttgart, however, are particularly keen on molds,and in particular the genus Aspergillus. They'realso enthusiastic about yeast and smut fungi.Why? "Fungi have long been indispensable forantibiotic production or in the food industry. Thefungi we employ help us to synthesize a variety ofchemicals in a CO2-neutral way. They're the basisfor detergents, emulsifiers, cosmetics andpharmaceuticals, pesticides, and plastics," saysProf. Steffen Rupp, deputy director of Fraunhofer

IGB and head of the Department of MolecularBiotechnology.

In contrast to petroleum, extracting chemicals fromrenewable raw materials doesn't release CO2 intothe atmosphere. And using fungi as productionorganisms has another major advantage: The poolof potential production organisms is almostinexhaustible, as is the range of renewable rawmaterials they can convert. As the fungi employ ahost of different metabolic pathways, they producean astonishing variety of products, which can beused in a wide range of applications.

From malic acid to bio-surfactants andpolyesters

Cells of the smut fungus Ustilago maydis at a single cellstage in presence of bio- surfactant crystals. Credit:Fraunhofer-Gesellschaft

Researchers at Fraunhofer IGB produce a widevariety of chemicals using fungi. One example ismalic acid. There is a continually growing market

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for the substance, which gives products such asjams and juices a sour taste and improves the shelflife of baked goods. It can also be used as abuilding block for bio-based polyesters. And, in aprocess similar to brewing beer, it can be producedusing molds. In beer brewing, the yeast fermentsthe malt sugar of the barley, while in malic acidproduction Aspergillus fungi convert sugar orvegetable oils.

This can be done by "feeding", for instance, a wood-based sugar solution to the fungi to get them togenerate malic acid. Fermentation like this workswell on a laboratory scale. The IGB researchers arecurrently investigating ways to scale up the processfor commercialization, in particular, by improvingthe fermentation yield.

Using a similar process, they can also createsurface-active agents that can be used to producedetergents, emulsifiers, active ingredients forcosmetics, pharmaceutics, and pesticides. That'swhere the smut fungi come into play. They'reparasites that infest plants, making them look likethey've been burned – hence their Germanic name,Brandpilze [burnt fungi]. "The process is anotherone we're actively developing for industrialproduction. Our principal goal is to optimize thecomposition of the biosurfactants we produce tosuit various applications in the field of detergentsand emulsifiers," explains Dr. Susanne Zibek, headof the Industrial Biotechnology Group.

Yeasts are also interesting producers. In addition tobrewing beer, as previously mentioned, certainyeasts can also be used to produce molecules thatare essential for synthesizing novel plastics, suchas long-chain dicarboxylic acids. The researchersat Fraunhofer IGB have succeeded in working out aprocess to produce long-chain dicarboxylic acidsfrom a strain of Candida.

Fermentation cascade of bioreactors with volumes of 10liters to 10 m3 at the Fraunhofer Center for Chemical-Biotechnological Processes in Leuna, Germany. Credit:Fraunhofer-Gesellschaft

Scaling up: the Fraunhofer pilot plant andbiorefinery

If the bio-based chemicals are to be used inindustrial applications – whether as surfactants, asfood components such as malic acid, or asmolecular building blocks for plastics – they'll needto be synthesized on a large scale. This is adaunting challenge: the worldwide production ofsurfactants, for instance, is 18 million metric tonsper year. "Scaling-up the processes from kilogramsto tons involves a great deal of engineering andcomputing," explains Fraunhofer researcher Zibek.

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There are still questions that need to be answered:How do we perfect the composition of thefermentation media? What's the best way to feedthe fungi? Researchers are initially addressing suchquestions on a small scale.

Once this hurdle has been cleared, the researchersat the Fraunhofer Center for Chemical-Biotechnological Processes CBP will then need toestablish the processes for large-scale production.They operate a pilot plant in which the fermentationprocesses can be scaled up to a maximum of tencubic meters. Such a huge volume requires anenormous amount of raw materials; after all, the fungi need feeding. The preferred source for thescientists is wood sugar, in other words, sugarsolutions that contain both glucose and xylose.These can be obtained directly in the FraunhoferCBP ligno-cellulose biorefinery and mixed into theculture medium.

In turn, this provides the molds and other fungalorganisms with optimal growth conditions using renewable raw materials, allowing them to producetons of chemicals.

Provided by Fraunhofer-GesellschaftAPA citation: Producing everyday products with fungi (2018, November 2) retrieved 25 March 2022 from https://phys.org/news/2018-11-everyday-products-fungi.html

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