SCIENCE
A bacterium that not only breaks down plastic waste but also uses it as food to power the breakdown process has been discovered.
The research, published in Frontiers in Microbiology, identified a new strain of Pseudomonas bacteria, a family known for its ability to withstand harsh conditions, such as high temperatures and acidic environments. The bacterium, which was found at a waste site where plastic had been dumped, is the first that is known to attack polyurethane.
Normally, when broken down, plastic can release toxic and carcinogenic chemicals, which would kill most bacteria, but the newly discovered strain is able to survive.
“These findings represent an important step in being able to reuse hard-to-recycle polyurethane products,” said Hermann Heipieper, at the Helmholtz Centre for Environmental Research-UFZ in Leipzig, Germany, who is one of the researchers. He said it might be ten years before the bacterium could be used big-scale and that in the meantime it was vital to reduce the use of plastic that is hard to recycle and to cut the amount of plastic in the environment.
Previous research has also shown that some fungi can break down PET plastic, while wax moth larvae — usually bred as fish bait — can eat up polythene bags. Fungi has been used before to break down polyurethane, but bacteria are much easier to harness for industrial use. Heipieper said the next step would be to identify the genes that code for the enzymes produced by the bug that break down the polyurethane.
Scientists revealed in 2018 that they had accidentally created a mutant enzyme that breaks down plastic drinks bottles, which are made of PET, potentially enabling the complete recycling of bottles for the first time. One of the team behind this advance, Prof John McGeehan, the director of the Centre for Enzyme Innovation at the University of Portsmouth, England, praised the new work.
“The breakdown of certain polyurethanes can release toxic additives, which need to be handled carefully. This research group has discovered a strain that can tackle some of these chemicals,” he said. “While there is still much work to be done, this is exciting and necessary research that demonstrates the power of looking to nature to find valuable biocatalysts. Understanding and harnessing such natural processes will open the door for innovative recycling solutions.”
More than eight billion tonnes of plastic has been produced since the 1950s and most has ended up in the world’s land and oceans, or in landfills.