Researchers make plastic-degrading enzyme effective

In 2016, Japanese researchers discovered that an enzyme from the bacteria Ideonella sakiensis is capable of degrading plastic waste. They made their discovery in a soil sample from a PET recycling plant in Osaka.

Now, a team of researchers at the Zurich University of Applied Sciences (ZHAW) are trying to modify this enzyme, named PETase, to make it more effective using a method called directed evolution. The winner of the Nobel Prize in Chemistry in 2018, directed evolution imitates the mechanisms of natural evolution in the laboratory to improve selected enzyme properties.

“By rewriting the enzyme’s blueprint, we can produce variants with a slightly different structure,” said Sean Hüppi from the ZHAW Institute of Chemistry and Biotechnology in Wädenswil. Using this method, the researchers have already been able to create several hundred variants of PETase. In a next step, they will add microplastics and then observe which enzyme variant can break down the plastic the fastest.

“We’re already seeing multiple improvements in enzyme activity after the first evolutionary changes,” said Hüppi.

The ZHAW research team is using artificial intelligence in the laboratory, which as Hüppi explains is capable of producing “entirely different deductive connections than humans”. They are working closely with a research group at the Institute for Machine Learning at the Swiss Federal Institute of Technology in Zurich (ETH) to develop the algorithms and analyse the data.

The ZHAW researchers have also been working with a specially designed automation solution in their laboratory since October, which was by a company called Tecan in Männedorf in the canton of Zurich. According to research director Rebecca Buller, the combination of machine learning and an automation solution will “further accelerate the laboratory evolution of PETase”.

The projected is funded through the new National Center of Competence in Research called Catalysis.