Something found in a dump may save the oceans
Humanity’s progress is marked by chance findings and lucky discoveries and this one might be one of the best.
In the 1950s the discovery of plastics seemed to be the solution to all our packaging and storage needs. Glass was great but heavy, expensive and fragile. Plastic was a wonder product that helped make a certain soft drink one of the most recognised brands on the planet and ensure that almost every human hand has held that plastic bottle at some point in their lives. That one brand alone revealed that they produce three million tonnes of plastic packaging a year in 2017. That would be equivalent to 200 000 bottles produced per minute or over 100 billion per year.
Some bottles do get recycled, some is reused for clothing but a big proportion is simply thrown away with a portion of that ending up in the sea.
They are by no means alone in the production of plastic and we as consumers could do a lot more to ensure a greater percentage is recycled, but there will always be some that does not.
The issue with plastics and in part the reason they work so well is that they do not degrade over time. That is perfect for keeping a product safe and fresh for the few weeks or even months you would like it to last, but it is so good, it will stick around for hundreds of years and even then it gets broken into smaller pieces rather than broken down into component parts that can be reused in the giant recycling chain that regulates all living and dead things on Earth.
A chance discovery at a recycling plant in Japan in 2016 could change all that, this is that story so far.
Nature finds a way
Everything is food for something else in nature and once something has been broken down to its component parts, the parts are used to produce food by combining them again until the food is used and broken down again. Most of those processes rely on a catalyst to allow the reactions to take place and the catalyst that we are focussing are proteins that we call enzymes.
To give you a sense of how fundamental they are to our functioning consider what temperature you are now. If you are not unwell you will be a toasty 37 degrees Celsius. Have you ever wondered why? Why 37 not 32 or 50 or 21 which is the temp that is most comfortable for us. Well, it is not about us, we convert a large percentage of our food to create heat and are grouped into a collection of animals known as warm blooded simply because the optimal operating temperature for most enzymes is 37 degrees. If you wondered why a fever, when our temperature reaches over 40, is so dangerous, it is because. enzymes denature at over 40 degrees, destroy the enzyme and we are no longer able to operate. Do the enzymes serve us or do we serve the enzymes?
Nature has many of these enzymes each specially adapted to build or break chemical components into bigger or smaller molecules. Adding or extracting energy each time they do.
When poly ethylene terephthalate(PET) exploded into the world in the 1970s it was a new molecule to nature, it was light, transparent, did not react chemically or electrically and was dense enough to withstand high pressures and form a barrier to stop gases from escaping - you can see why it makes for the perfect carbonated drink bottle. But the other reason it was so durable was that nothing in nature could break it down. As its popularity grew and we happily converted to an instant-gratification-disposable-consumer lifestyle, we did not think about the consequence. Dozens of other plastics also all new to nature were being created and distributed through the world and now 50 years later we are seeing the problem with creating indestructible packing for disposable items.
But nature finds a way, plastics are made from oil which for the most part is a compressed and partly decomposed plants and animals. Some plants in an attempt to protect themselves from the environment and ward off attacks developed the ability to create a molecule called cutin, plants beat us to making plastics as the cutin molecule is similar to the polymers in plastics. Given how long plants have been around bacteria developed the ability to create enzymes that could break down cutin. It was a form of this enzyme which some time over the last 50 years developed the ability to break down PET, we just did not know about it and did not see much of it in the wild. That changed in 2016 when Japanese scientists examining the holding area of a recycling plant in Sakai in Japan noticed some bottles were covered in an ooze that appeared to have broken down some of the bottle.
Back in the lab they identified a new type of bacteria they called Ideonella sakaiensis, a bacteria with an enzyme that could break down plastic not in hundreds of years, but just a few years and it did not just create smaller pieces of plastic it resulted in environmentally safe molecules.
In the years that most of the world and over half of Americans were surprised to find they had elected a reality TV person as their President, scientists had discovered a potential breakthrough.
What is an enzyme?
The simplest explanation is that they are catalysts that allow chemical reactions to occur under conditions when they otherwise would not. Not only do they facilitate and speed up the creation or breakdown of molecules they don’t get consumed in the process and so can repeat the action many times.
There are quite a few additional elements that allow it all to work which I would encourage you to read about, but for the scope of this piece you just need to know that they are everywhere and they are amazing. If you would like to see one in action, take a water biscuit and chew it in your mouth but don’t swallow, the dry and tasteless biscuit will begin to taste sweet after a few minutes. Biscuits are made of carbohydrates which when broken down result in sugar. You have an enzyme in your saliva that breaks down carbohydrates and so while waiting you can taste your enzymes at work in your mouth.
Years to biodegrade is not good enough
It joined a list of other organisms and enzymes that were discovered to break down plastics, but this was the big one, but there was still a problem - the plastic mountain would continue to grow because the bacteria could not break it down fast enough.
The research continued in labs around the world but the next advance would come in 2018 from a lab in the UK. While trying to isolate the enzyme in the bacteria with the hope of producing just the enzyme rather than have to cultivate the bacteria they were able to isolate it, this is when they realised it was related to cutinase that could break down plant cutins and named it PETase after the PET polymer. While trying to replicate it they happen to find a mutation that not only could break down the plastic in years, it could do so in days. This would allow us to break down the plastic as fast as we were creating it.
PETase: this weird looking string-like molecule just might help us avoid ruining the planet
Excellent, so the researchers are now rich and waiting for the Nobel Prizes?
Not quite, a major challenge with so many breakthroughs created in the lab is being able to scale it in order to work in industrial settings.
That brings us to 2020. The next requires funds to determine the best methods to both optimally produce the enzyme and then to determine under what conditions it will work best.
To do that will require institutions and government, business and plastic manufacturers to get involved. Already there are a growing number of teams that have taken up the challenge, but like trying to find a vaccine for Covid-19 a small team will take decades to succeed but a global team might solve it in just a few years. We need to decide how long we can afford to wait to find the fix. It is unlikely that we are going to use less plastic anytime soon so we need to find a way to break it down.
We don’t want to wait until there is more plastic than fish in the ocean to get there either.
Source : https://en.wikipedia.org/wiki/PETase#/media/File:PETase_5XH3_with_HEMT-cartoon.png
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