CRI听力:Scientists engineer mutant enzyme which eats plastics quickly

Scientists in Britain and the United States say they have engineered a plastic-eating enzyme that could in future help in the fight against pollution.

The enzyme is able to digest PET - a form of plastic patented in the 1940s and now used in millions of tonnes of plastic bottles.

According to the British Plastics Federation, bottles made from PET are used to package 70% of soft drinks, fruit juices and mineral waters sold in stores.

PET plastics can persist for hundreds of years in the environment.

Professor John McGeehan from Britain's University of Portsmouth says recycling is not keeping up with the production of plastics and it's time for scientists to use all the technology available to eradicate the problem.

"From the 1950s onwards the amount of plastic we are using it's just gone exponential. It's such an incredibly useful material for packaging. But also remember for the polyesters in your clothing and carpets and all those even medical devices, plastics have transformed our world. And that's not going to change."

The scientists have re-engineered an active region of the molecule, resulting in a mutant protein with an enhanced ability to attack plastic.

Professor McGeehan explains:

"What we're able to do is following on from the Japanese study is take the gene out of that bacteria and make the enzyme in the lab under control conditions. We can now generate grams of the enzyme. And in partnership with industry we should be able to generate kilograms of the enzyme. What we really need to do though is make it faster in order to make a real environmental solution. So we're quite a way off that yet, but this is a major step forward."

Professor McGeehan says the aim is to scale up the project so that it can be produced on an industrial scale.

"What we've done is we've pulled out the enzyme from that bacteria and grown it up in the lab. And now we can actually digest PET within days much quicker than in the environment. And the idea here is that we can make the enzyme faster now by understanding how it works and then we have an industrial process."

The enzyme study is published in the Proceedings of the National Academy of Sciences (PNAS).

The team says there is room to further improve the enzymes, making them act much faster.

Independent scientists not directly involved with the research have said it is exciting news but cautioned that the enzyme's development as a potential solution for pollution is still at an early stage.