‘Promiscuous’ enzyme offers new source of sustainable materials

A newly discovered family of enzymes can convert plant waste into sustainable and high-value products such as nylon, plastics, chemicals and fuels, academics at the University of Portsmouth have said.

Researchers said the new family of enzymes was active on the building blocks of lignin – one of the main components of plants.

Professor John McGeehan, director of Portsmouth’s Institute of Biological and Biomedical Sciences, said: “Enzymes are biological catalysts that can perform incredible reactions, breaking down some of our toughest natural and man-made polymers.

“To protect their sugar-containing cellulose, plants have evolved a fascinatingly complicated material called lignin that only a small selection of fungi and bacteria can tackle.

“However, lignin represents a vast potential source of sustainable chemicals, so if we can find a way to extract and use those building blocks, we can create great things.”

Lignin is central to water delivery in plants and provides strength and defence against pathogens. The enzyme is a new class of cytochrome P450 and is ‘promiscuous’, meaning in scientific terms that it is able to work on a wide range of molecules.

Professor McGeehan said the research team found a way of releasing a key bottleneck in the process of breaking down lignin to its basic chemicals. The results provide a route to making new materials and chemicals such as nylon, bioplastics and even carbon fibre from what has previously been a waste product. This would also reduce reliance on oil to make such products, helping to decrease CO2 emissions.

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