Researchers at the University of Texas have just developed an enzyme capable of breaking down PET plastic in less than 24 hours; a symbolic bar that paves the way for very large-scale recycling of this first-category pollutant.
From the highest peaks to the deepest pits, plastics are found everywhere in our environment today. This is obviously a major ecological problem, as they traditionally take a long time to decompose. So research is working hard to find a way to speed up the process; in works identified by ScienceAlerta team from the University of Texas has just taken a big step in this direction by developing an enzyme capable of achieving this in just a few hours.
Very briefly, an enzyme is a substance that acts as a biological catalyst; that means she can initiate or accelerate a chemical reaction. They are leading players in life; they are essential to the life cycles of the majority of living organisms. We can, for example, cite the proteases that break the bonds that hold proteins together, or lipases which catalyze the breakdown of fats.
PET decomposed in less than 24 hours
With the current boom in bioengineering, researchers regularly develop heaps of artificial enzymes that can catalyze many chemical reactions essential to industrial processes; they are found in the food industry, in agriculture, in the pharmaceutical industry, etc.
The researchers thus started from a natural enzyme called PETase. As its name suggests, it is known for its ability to break down plastic PET. It is one of the most used plastics, especially in packaging that often ends up in nature. They then used a system based on artificial intelligence. It enabled them to identify five mutations likely to increase the catalytic activity of PETase.
This allowed them to come up with a new enzyme, this time called FAST-PETase for Functional, Active, Stable and Tolerant PETase. It has been shown to be able to catalyze the decomposition of these plastics in record time; depending on the different containers tested, the enzyme can complete its task in days or even hours.
The chemical arsenal of a plastic-eating bacterium
This is a very impressive number; remember that it usually takes years, even centuries, for these plastics to decompose in nature. And this approach based on FAST-PETase is even faster than all the other techniques tested at this time.
Many studies have, for example, been carried out on Ideonella sakaiensis. It’s about a bacteria discovered in 2016 which has the particularity of being able to break down PET to feed on it. Unfortunately, this takes dozens of weeks to decompose small samples that are less resistant than a real PET bottle. It is therefore not suitable for use on an industrial scale.
By studying it more closely, the researchers ended up discovering the element responsible for this rare faculty in 2016: it is precisely the famous PETase mentioned above. Once isolated and purified, this enzyme made it possible to considerably speed up the process by breaking down PET within days.
Finally, recycling on a very large scale?
A figure that was beginning to look promising; and doing it go below 24 hours with their new FAST-PETasethe University of Texas potentially comes to pave the way for the first large-scale industrial enzymatic plastic recycling channels.
The term recycling is not chosen at random. Because FAST-PETase not only reduces plastic to an unusable mush; she the depolymerizes, that is, it cuts it into small units which can then be reassembled. Researchers have also shown that it is possible to produce new plastics from the products of degradation!
Moreover, this enzyme can work at room temperature, which constitutes a very important advantage in real conditions. So we end up with a particularly promising approach for the industry, but also and above all for the environment. Indeed, recycling more plastic means less of it will be piled up to eternal life in landfills or burned, with all that this implies in terms of energy expenditure and toxicity.
“This work demonstrates the power of a multidisciplinary approach, with notions drawn from synthetic biology, chemical engineering and artificial intelligence.”, welcomes the biochemist Andrew Ellington.
Source: Journal du Geek by www.journaldugeek.com.
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