BIOTECHNOLOGY
it had evolved to digest artificial plastics , given PET has only been around since the 1940s – a very short period for an evolutionary adjustment .
The researchers could see that the structure of the enzyme was similar to one evolved by bacteria to break down cutin , a natural polymer used by plants as a protective coating . The team was manipulating the enzyme to explore this connection when they unintentionally improved its PET-digesting ability .
Collaborating NREL scientists Dr Bryon Donohoe and Dr Nic Rorrer subsequently tested PETase on PET samples from drink bottles . Observing with an electron microscope , they saw the PETase enzyme begin degrading the pieces of PET plastic after just four days .
The researchers knew they were only at an early stage and that further engineering could potentially make the enzyme work much faster and be a genuine tool for revolutionising plastics recycling .
Our new ‘ biotech ’ ally
Another family of enzymes has been found that can be engineered to break down plant waste and help convert it into high-value materials such as nylon , plastics and other polymers .
This has the potential , if scaled up , to achieve two sustainability goals : to give waste , particularly crop waste , a commercial value while also replacing petroleum-based feed stocks for such products with low-carbon renewables .
The latest development was announced in mid-2019 by a UK – US enzyme engineering team a t the University of Portsmouth and the US Department of Energy ' s National Renewable Energy Laboratory ( NREL ).
The team ’ s newly engineered enzyme is active on a key component of lignin . Currently , this valuable material is primarily burned , and scientists have been trying for decades to find a way to break it down efficiently . work , then engineered to produce new tools for the biotechnology industry .
“ In this case , we have taken a naturally occurring enzyme and engineered it to perform a key reaction in the breakdown of one of the toughest natural plant polymers – lignin .
“ To protect their sugar-containing cellulose , plants have evolved this fascinatingly complicated material that only a small selection of fungi and bacteria can tackle . However , lignin represents a vast potential
PHOTO : WIKIMEDIA COMMONS source of sustainable chemicals , so if we can find a way to extract and use those building blocks , we can create great things .”
Lignin acts as scaffolding in plants and is central to water delivery from roots . It provides strength and also a defence against pathogens .
“ It ’ s an amazing material ,” says Professor McGeehan . “ Cellulose and lignin are among the most abundant biopolymers on earth . The success of plants is largely due to the clever
Professor John McGeehan , Director of the Centre for Enzyme Innovation at the University , says the finding arises from the researchers ’ pursuit of enzymes in nature that can be brought into the laboratory , studied to see how they
Panoramic image taken of a section of the Diamond Light Source synchrotron , inside the experimental hall .
18 REVOLUTION PLASTICS / 2023