Coast KZN

17 Sep 2018

Scientists engineer mutant enzyme that eats plastic bottles

(Zululand Observer)

“The enzyme is able to digest PET (polyethylene terephthalate) – the material used in the plastic bottles that are clogging up landfills, coastlines and oceans around the world. ”

Researchers in the UK and the U.S. have accidentally engineered an enzyme that eats plastic. The enzyme, which is able to digest PET (polyethylene terephthalate), was discovered by chance. Scientists from the University of Portsmouth in the UK and the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) were examining the structure of a natural bacterium, Ideonella sakaiensis which was found in 2016 at a Japanese waste recycling centre. The bacterium uses an enzyme to break down PET plastic, but not fast enough. To understand how Ideonella sakaiensis evolved, the research team tweaked the structure of the enzyme, PETase, by adding some amino acids. In the process they created an enzyme that worked faster than the natural one. The scientists found that the new PETase mutant works better than the natural PETase in degrading PET.

Professor John McGeehan from the University of Portsmouth, who co-led the work, said that serendipity often plays a significant role in fundamental scientific research and their discovery is no exception. PETase, the modified enzyme, can break down PET in a few days. This amazing discovery could contribute to the world’s war against plastic pollution.

Proper recycling now possible
PETase reverses the manufacturing process by reducing polyesters back to their building blocks so they can be used again, BBC News reported. This could revolutionize the recycling process, allowing plastics to be re-used more effectively. Plastic bottles are seldom made from recycled plastic. Plastic bottles that do get recycled are usually turned into polyester fibres for carpets or fabric. With this discovery plastic bottles can be turned back into plastic bottles.

Professor McGeehan told BBC News: “They could be used to make more plastic and that would avoid using any more oil. Then basically we’d close the loop. We’d actually have proper recycling.”
About one million plastic bottles are purchased around the world every minute, with that number predicted to increase another 20 percent by 2021.