Why haven’t plastic-eating bacteria repaired the ocean yet?

Scientists at the University of Texas have announced they’ve created a plastic-eating enzyme that could save billions of pounds of plastic from ending up in landfills.

Now, if that phrase gives you deja vu, you’re not alone.

Science news followers may have seen similar exciting headlines over the years, from the 2008 science fair project Isolates Plastic-Eating Microbes – about a 17-year-old science fair winner who got bacteria to degrade plastic bags by 43% – in last month’s New Enzyme discovery is a new step towards the fight against plastic waste, in which British scientists have developed an enzyme capable of breaking down the PTA, an ingredient in plastic bottles.

You’ve seen a lot of similar headlines between the two: “A new super-enzyme eats plastic bottles six times faster”, “Plastic-eating bacteria could help global recycling efforts”, etc., which give the impression of a miracle solution (itself undoubtedly recyclable) that will solve our monstrous plastic problem.

Why are these plastic-eating bacteria just twiddling their thumbs? We have a crisis to manage !

So what’s taking so long? Why are these bacteria just twiddling their thumbs when we have a crisis treat ?

It turns out that there are several reasons why things are not so simple:

Plastic is not the same at all. Many enzymes or bacteria only work for one specific type of plastic, and much of our waste combines multiple types of plastic.

Most plastic recycling efforts focus on PET, the plastic used in plastic bottles. PET accounts for approximately 20% of global plastic waste. It is chemically easier to break down than polyethylene or polypropylene, types used in plastic films and food packaging.

This is an important caveat: most of these solutions would only make our plastic problem worse, rather than solving it entirely.

Many solutions only work under specific conditions. Often reactions or bacteria only work at certain temperatures, in special environments or after long periods of time. The harder it is to create the conditions, the less practical it is to do it on a large scale. It also means that bacteria are unlikely to solve the problem of plastic pollution already present in nature – more on that soon.

They cost too much. These processes can be expensive. Additionally, most solutions simply break plastic down into its original monomers, which are really only useful for creating more plastic.

This poses two problems: first, it does not reduce the amount of plastic in the world, and second, making new plastic is already really cheap. Creating an expensive factory, shipping tons of junk there, and having bacteria slowly produce ingredients that are virtually worthless – and still aren’t biodegradable – isn’t a great business model or even an effective use of corporate funds. taxpayers.

It is not necessarily safe or effective to release it into the wild. It is often assumed that this bacterium could be released to eat away at the mountains of plastic that we currently have buried in landfills, swirled around in the oceans or scattered as trash.

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But even if bacteria or enzymes could operate under totally unregulated conditions, they could have toxic by-products, destroy plastic still in use (like, say, the device you’re using to read this right now, you preventing you from finishing that valuable item), or demanding to release huge amounts in an area to make a difference.

So for now, these technologies could really only be used in our existing recycling systems, rather than being a fundamentally new alternative. We will still need to sort, collect and process all the plastic we want bacteria to eat.

Fortunately, there’s good news too: Scientists from Japan to Saudi Arabia to the US National Renewable Energy Laboratory are working on these issues, and things are looking up.

For example, the recent discovery at UT-Austin identified an enzyme that reduces plastic breakdown time to hours and can operate at the relatively attainable temperature of 50°C (122°F). And it was found using an AI algorithm that could keep iterating and improving its performance.

Fortunately, there is also good news: scientists from the United States to Saudi Arabia to Japan are working on these problems, and things are looking up.

And the first demonstration plant dedicated to the enzymatic recycling of plastic has just opened. The French company Carbios, which runs it, has announced that it has successfully produced new plastic bottles from PET with a process that makes them infinitely recyclable.

This is a breakthrough worth celebrating. Today, even if plastic is recycled (more than 80% is not, including more than 90% in the United States), it can generally only be transformed into lower quality plastic, for uses of niche like the carpet.

Traditional mechanical recycling processes are expensive and inefficient, requiring sorting, shredding, cleaning, melting and granulation of waste and disposal of any batches contaminated with incompatible foods or materials. Chemical recycling processes can often create their own toxic by-products.

Carbios plans to create a commercial-scale facility by 2024, and while they don’t expect their plastic to be as cheap as the freshly made varieties, they hope businesses and conscious consumers environment will pay a little more for it. In addition, his approach will make it possible to recycle plastic from mixed waste more efficiently and with less waste.

We don’t have to rely on miracle bacteria to do our dirty work.

Time will tell if new processes will help solve our plastic problem. Meanwhile, other scientists and companies are creating biodegradable materials that can completely replace plastics, from MIT’s cellulose-based solution to companies using bacteria to grow sustainable materials. European governments are taking another approach and banning harder-to-recycle plastics.

And of course, you don’t have to wait for one of them – people all over the world are finding creative ways to reduce their own plastic use. As exciting as they are, we don’t have to rely on miracle bacteria to do our dirty work.

This article was originally published by our sister site, Freethink.

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