The results have been published earlier this year in Chemistry, A European Journal, also featuring their co-workers Eman Abdelraheem, Vasilis Tseliou, Jessica Desport, and Masashi Serizawa. Mutti and Gargano are now exploring further cooperation with industry -  not only in polymer analysis but also in polymer recycling, which can benefit from the use of highly active enzymes for polymer degradation.

Engineered enzymes

For the research published in Chemistry, A European Journal, Mutti engineered a cutinase enzyme for selectively hydrolysing the ester bond of polyesters – cutting the polymer chain at well-defined places. Gargano then used this in an analytical workflow, analysing the fragments and using this information to determine the polymer’s exact composition and structure.

Mutti: ‘A major challenge now is to extend the concept beyond the realm of polyesters. As challenging as the enzymatic depolymerisation of real-life polyester samples might have been, from a biocatalytic point of view, the polyester moiety is relatively simple. We only had to focus on hydrolytic enzymes that just need water to do their work.'

'When we translate this concept to other polymers, we will encounter many challenges. Amongst others, we will need to develop specialist enzymes for depolymerizing the relevant synthetic polymer types such as polyamides, polyurethanes, polyethers, or even highly challenging polyolefins such as polyethylene and similar. These enzymes will be more complex in their operation, for instance in some cases requiring cofactors.'

Potential for recycling

Another aspect to further explore is the potential of using enzymatic depolymerisation for degradation and recycling of polymers. Mutti: ‘We have developed many insights in the working of these enzymes that enabled us to improve their catalytic properties, including their specificity. This knowledge can also be applied to enzymatic depolymerisation of polymers, so that they can be chemically recycled. There are many polymers out there where depolymerisation is a real challenge. We think enzymes can have a lot of potential there.’

Gargano: ‘As researchers, we see the potential, but we have to establish the interest of the industry in this.’ He is already reaching out to potential novel partners, which has led to some promising contacts and small-scale cooperation. Mutti has discussed the project outcome with various partners in the polymer industry as well as companies working on enzymes. ‘We definitely want to explore the possibility of establishing a consortium of academia and industry to further develop this and obtain funding, for instance through the Horizon Europe programme.’

Working on ‘the real stuff’

Both Mutti and Gargano enjoyed the cooperation with industry. Mutti: ‘It allowed us to work on the real stuff, on real industrial polymer samples. This provided the ultimate test of our proposed enzymatic degradation.

Gargano adds: ‘We have performed early stage work that in itself was successful. But it does not provide a method that can be implemented in industry right away. I find it positive that our industry partners were quite understanding that this project was about establishing proof of principle. ’

At times, the complexity of the research was daunting since it required biocatalysis, molecular biology, in vitro assay testing for catalytic activity, comprehensive analytical chemistry as well as knowledge in polymer chemistry. ‘Of course one can’t expect a single postdoc to cover all those fields. Only because other people in our groups assisted with knowledge and expertise we were able to pull it off,’ says Mutti. Gargano adds: ‘Everybody gave it the necessary energy. This just shows our strong willingness to make this a success!’

Paper details

Eman Abdelraheem, Vasilis Tseliou, Jessica Desport, Masashi Serizawa, Martin Schürmann, Paul Buijsen, Ron Peters, Andrea F. G. Gargano, Francesco G. Mutti: Selective Hydrolysis by Engineered Cutinases: Characterization of Aliphatic-Aromatic Homo and Co-Polyesters by LC and LC–MS Methods Chem. Eur. J. 2025, e202403879 DOI: 10.1002/chem.202403879

See also

• Research group Andrea Gargano: Chemometrics & Advanced Separations
• Research group Francesco Mutti: HIMS-Biocat
• Van ‘t Hoff Institute for Molecular Sciences