Enzymes are now indispensable for many industrial sectors. Their potential to naturally refine products or accelerate production processes as catalysts makes protein molecules secret stars of biotechnological processes. Detergent manufacturers in particular can no longer do without these multi-talents. More and more textiles today consist of a mixture of fibers - such as cotton and polyester. In addition, there are new materials for outdoor textiles made mainly from synthetic fibers. This also poses new challenges for detergents. A particular problem here is the unsightly pilling that occurs on the textile surface after repeated washing.
Synthetic fibers at a glance
The strategic alliance "Functionalization of Polymers" (FuPol) has taken up these and other challenges. Coordinated by the Monheim enzyme specialist evoxx technologies GmbH, nine partners from research and industry have been tackling different challenges for more than five years. These include enzymes for detergents that are used to prevent pilling in the first place or to remove existing pilling in textiles that consist entirely or partly of synthetic fibers. The work of the entire consortium was funded from 2013 to 2018 with a total of 8 million euros by the Federal Ministry of Education and Research (BMBF) as part of the "Industrial Biotechnology Innovation Initiative".
In the first stage until 2016, the project partners were able to identify enzymes that have the potential to nibble off the unpleasant lumps. While browsing through the bioarchive, the biotechnologists of the consortium discovered esterases such as cutinases that break ester bonds and attack natural substrates. "Cutinase is an enzyme used by various fungi to penetrate the cutin layer of leaves," explains Michael Puls, Managing Director of evoxx. "This is a kind of wax layer with which plants protect themselves against pathogens and dehydration. Cutinases are therefore enzymes that attack such layers of wax".
Fight pilling with enzymes
The aim of the second phase, which ended in April 2018, was to improve the activity of the promising candidates and at the same time optimize the production process with a view to industrial application. This work was funded by the BMBF with around 166,000 euros. The focus here was not only on the further development of fiber-lump-degrading enzymes for detergents. The textile industry is also very interested in biotechnological and thus sustainable approaches in the processing of yarns and fabrics, for example in order to combat undesirable residues from fiber production in an environmentally friendly way instead of using chemical substances. "For example, shorter polymer residues lead to difficulties in the subsequent processing of the yarns. These could be removed more sustainably with the aid of enzymes," says Puls.
PET-degrading enzymes identified
In order to improve the activity of the enzymes, the researchers created mutations in the gene encoding the respective enzyme and thus altered its structure. But that' s not all. They modified the so-called binding domain in order to enhance the desired effect of the enzymes. "We have found esterases that degrade PET quite efficiently. We have also developed improved enzyme variants and considerably improved the producibility of the enzymes. This could lead to economic efficiency in the foreseeable future and the application of the enzymes in detergents would then be on the horizon," concludes Puls. Washing tests have already confirmed the so-called anti-pilling effect. The team also succeeded in using optimized PET hydrolysis not only to break down textile fibers, but also to significantly change the surfaces of thin films.
The FuPol Alliance at a glance:
Project coordinator: evoxx technologies GmbH (previously evocatal GmbH)
Industrial partners: evoxx technologies GmbH, AB Enzymes GmbH, Henkel GmbH & Co. KGaA, Coats Opti Germany GmbH
Academic Partners: RWTH Aachen, DWI – Leibniz Institute for Interactive Materials e.V., Fraunhofer IAP, University Leipzig, University Hamburg
Functionalizing synthetic fibers
In addition to enzymes that degrade PET fibers during washing, the consortium wanted to functionalize synthetic fibers in such a way that certain properties could be achieved. The antimicrobial protein LCI was used for this purpose. The researchers focused on dyeability, which was to be enhanced with the help of binding domains. "The binding domain can be used to improve the binding reactions so that as much of the protein as possible remains attached to the fiber. The project partners wanted to use it to treat the surfaces of textiles in order to absorb more colour or to produce other properties," explains Puls. The binding domain was used to achieve preliminary effects, but not in the desired quality. According to Puls, further research is required in order to improve the binding properties.
Refined enzymes decompose plastic molecules
The use of PET esterases in detergents continues to be of interest. The best candidates have already been patented by the project partners Henkel and evoxx. evoxx is currently investigating whether the enzyme candidates can be used for other purposes. It is already evident, however, that the potential of the refined enzymes is far greater. "Possible applications could be anywhere where PET plastic fibers are a problem, such as microplastics. With these enzymes, plastic can actually be broken down into its monomers and the raw materials made available again. The enzymes could also be used for wastewater treatment," said Puls.
Autorin: Beatrix Boldt