Insects Across The Globe Evolve To Eat Plastic, Study Finds | Plastics

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Microbes in oceans and soils around the world are evolving to eat plastic, study finds.

The research analyzed more than 200 million genes found in DNA samples taken from the environment and found 30,000 different enzymes that could break down 10 different types of plastic.

The study is the first large-scale global assessment of the plastic degradation potential of bacteria and found that one in four organisms analyzed carried an appropriate enzyme. The researchers found that the number and type of enzymes discovered matched the amount and type of plastic pollution in different places.

The results “provide evidence of a measurable effect of plastic pollution on the global microbial ecology,” the scientists said.

Millions of tons of plastic are dumped into the environment every year, and pollution is now pervading the planet, from the top of Mount Everest to the deepest oceans. Reducing the amount of plastic used is vital, as is the proper collection and treatment of waste.

But many plastics are currently difficult to degrade and recycle. Using enzymes to quickly break down plastics into their building blocks would allow new products to be made from old ones, reducing the need for virgin plastic production. The new research provides many new enzymes to study and adapt for industrial use.

“We found several sources of evidence supporting that the potential for plastic degradation of the global microbiome is strongly correlated with measurements of environmental plastic pollution – a significant demonstration of how the environment responds to pressures that we impose, ”said Professor Aleksej Zelezniak. , at Chalmers University of Technology in Sweden.

Jan Zrimec, also at Chalmers University, said: “We didn’t expect to find so many enzymes in so many different microbes and environmental habitats. It is a surprising discovery which illustrates the extent of the problem.

The explosion in plastic production over the past 70 years, from 2 million tonnes to 380 million tonnes per year, has given microbes time to evolve to cope with plastic, the researchers said. The study, published in the journal Microbial Ecology, began by compiling a data set of 95 microbial enzymes already known to break down plastic, often found in bacteria in landfills and similar places full of plastic.

The team then looked for similar enzymes in environmental DNA samples taken by other researchers from 236 different locations around the world. Importantly, the researchers ruled out potential false positives by comparing the enzymes initially identified with enzymes from the human gut, which is not known to have plastic-degrading enzymes.

About 12,000 of the new enzymes were found in ocean samples taken from 67 locations and three different depths. The results showed consistently higher levels of degrading enzymes at deeper levels, matching the higher levels of plastic pollution known to exist at shallower depths.

Soil samples were taken from 169 sites in 38 countries and 11 different habitats and contained 18,000 plastic-degrading enzymes. Soils are known to contain more plastics with phthalate additives than oceans, and researchers have found more enzymes that attack these chemicals in soil samples.

Almost 60% of the new enzymes do not belong to any known class of enzymes, the scientists said, suggesting that these molecules break down plastics in ways that were previously unknown.

“The next step would be to test the most promising enzyme candidates in the laboratory to closely study their properties and the rate of plastic degradation they can achieve,” Zelezniak said. “From there, you could design microbial communities with targeted degradation functions for specific types of polymers. “

The first insect that eats plastic was discovered in a Japanese landfill in 2016. Scientists then modified it in 2018 to try to learn more about its evolution, but inadvertently created an even better enzyme to break down bottles. in plastic. Further adjustments in 2020 increased the rate of degradation six-fold.

Another mutant enzyme was created in 2020 by the company Carbios which breaks down plastic bottles for recycling within hours. German scientists have also discovered a bacteria that feeds on the poisonous polyurethane plastic, which is usually dumped in landfills.

Last week, scientists revealed that levels of microplastics known to be consumed by humans through their food cause damage to human cells in the lab.

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