Exactly two years later, the same team has once again outdone itself. By mixing a newly discovered enzyme with the old version, they have created a new super mutant enzyme that efficiently breaks down PET.
The huge increase in efficiency may represent a potential avenue for future plastic recycling, although at the moment, avoiding plastic products is still the most effective way to manage our pollution.
Today, man-made plastic waste has invaded almost every crack of our planet, and PET (aka polyethylene terephthalate) is the most common thermoplastic of them all, commonly used in water bottles and clothing.
It takes centuries for this plastic to completely break down in the natural world, but even in no time these products are present on our planet, some microbes have discovered how to get through them in just days Have to create.
In 2016, these organisms were first discovered at a recycling plant in Japan – Ideonella sakaiensis. Over the years, research has shown that it secretes a plastic-degrading enzyme called PETAS to break down PET-water bottles.
Now, we have done a second search, and labeled it MHETase. Together, the two enzymes form the right plastic-destroying partnership.
While Paytas breaks the plastic surface, researchers say the new enzymes cut things even further, promising to essentially recycling plastic until all the remaining basic building blocks are in place.
“[I]It was natural to see if we could use them together, mimicking what happens in nature, ”explains structural biologist John McGihan, who has been part of research at the University of Portsmouth from the beginning.
Simply mixing PETase with the new enzyme MHETase was sufficient to double the breakdown of PET. But when scientists physically connected them to “two pac-men with one wire”, they worked even better.
Using the powerful Diamond Light Source synchrotron as a source for powerful X-ray beams in the UK, McGihan and his colleagues revealed the structure of the new enzyme through X-ray crystallography, which then made them an indivisible one. Allowed to engage both painstakingly. pair.
“It took a lot of work on both sides of the Atlantic, but it was worth the effort,” McGihan says.
“[W]E was happy to see that our new chimeric enzyme is three times faster than naturally developed isolated enzymes, opening up new avenues for further improvement. ”
In nature, it is not uncommon for micro-secreting enzymes to work with each other, breaking down cellulose, chitin, and other hard cell structures.
“Given that natural microbial systems have been evolving for millions of years, it may not be surprising to find soil bacteria such as soil bacteria, to incorrectly degrade the recycled polymer. I. Sakinesis Developed the ability to use [..] A two-enzyme system, ”the authors write.
When plastics try to engineer faster and more efficient ways to break down waste, researchers find that a cocktail of plastic-blasting enzymes is likely to be better than just one person – and this super mutant destroyer is certainly Se may be a piece in that puzzle.
“Going forward, the design of multienzyme systems for the reduction of mixed polymer wastes is a promising and fruitful area for continued investigation,” the team concludes in their paper.
The study was published in Proceedings of the National Academy of Science.