Industrial enzymes are widely used in, for example, washing powders and biofuel production, They have been made to work up to 1,000 times faster in a few years, the same timescale McGeehan envisages for the plastic-eating enzyme. A patent has been filed on the specific mutant enzyme by the Portsmouth researchers and those from the US National Renewable Energy Laboratory in Colorado.
One possible improvement being explored is to transplant the mutant enzyme into an “extremophile bacteria” that can survive temperatures above 70C, at which point PET changes from a glassy to a viscous state, making it likely to degrade 10-100 times faster.
Earlier work had shown that some fungi can break down PET plastic, which makes up about 20% of global plastic production. But bacteria are far easier to harness for industrial uses.
Other types of plastic could be broken down by bacteria currently evolving in the environment, McGeehan said: “People are now searching vigorously for those.” PET sinks in seawater but some scientists have conjectured that plastic-eating bugs might one day be sprayed on the huge plastic garbage patches in the oceans to clean them up.
“I think [the new research] is very exciting work, showing there is strong potential to use enzyme technology to help with society’s growing waste problem,” said Oliver Jones, a chemist at RMIT University in Melbourne, Australia, and not part of the research team.
“Enzymes are non-toxic, biodegradable and can be produced in large amounts by microorganisms,” he said. “There is still a way to go before you could recycle large amounts of plastic with enzymes, and reducing the amount of plastic produced in the first place might, perhaps, be preferable. [But] this is certainly a step in a positive direction.”