An accidental scientific advancement has scientists very excited about the future of recycling plastic water bottles. This research into an evolutionary phenomenon has opened the gates to new possibilities concerning the global plastic pollution problem. Plastic pollution has met its match in a mutant enzyme that eats plastic water bottles. Plastic bottles often take decades to break down and are resistant to most biodegrading. Until now, that is.
The Study That Started It AllScientists discovered a bacteria with a shocking diet at a waste dump in Japan in 2016. It was the first bacteria to naturally evolve to eat plastic. The enzyme the bug produced was what scientists were studying in depth when the accidental discovery occurred. A research team led by Professor John McGeehan at the University of Portsmouth set to work studying the enzyme.
Three stages of enzymes breaking down plastic during a 96 hour period (A-C) - Magnified 3000 times."Characterization and engineering of a plastic-degrading aromatic polyesterase," PNAS (2018)[/caption] The original intention was to tweak the enzyme to see its' evolution process. However, while conducting tests the team discovered they had increased the molecules efficiency at breaking down PET! One of the notoriously difficult plastic components to break down is PET (or polyethylene terephthalate plastic). Water and soft drink bottle plastic contains a great deal of PET. In fact, it can take many decades to break down in ocean waters. However, this mutant enzyme takes just a few days to start the breakdown process. With the accidental improvements happening already researchers believe this can be sped up further. The future goal is to make a large-scale process to enable recycling.
Some Accidents Are Happy Accidents
The team was studying the enzyme using powerful beams of X-Rays when the tweak occurred. Basically, the researchers noticed the enzyme had a similar molecule structure to one that breaks down cutin. Cutin is a protective natural polymer on plants to prevent damage. While manipulating the enzyme to examine the connection, the improvement occurred. As a result, the bugs ability to break down the PET was honed. Professor McGeehan estimates the improvement at 20%. While this is a big improvement, he believes the enzyme can be optimized further. With the advancements made in enzyme modification in other areas, this spells great news. Superbugs have been optimized for other purposes and fields. McGeehan believes a similar process can happen here.
Researchers still have several theories to explore. One is transplanting the enzyme into a certain kind of bacteria that withstands high temperatures. PET turns into a viscous fluid at 70C, which could speed up degradation up to 100 times faster. This discovery of the enzyme has opened up a world of possibilities for researchers and the future of recycling.
A Vision For Recycling Plastic Water Bottles
Researchers think the enzyme can revert plastic water and soft drink bottles back to their basic, clear plastic state. Currently, consumers purchase 1 million plastic bottles a minute globally. Even with recycling efforts ramping up, it's not enough. Recycling plants for the 14% returned can only turn bottles into an opaque fiber with limited use. Therefore, if recycling plants revert bottles to clear plastic, demand for production would decrease. This would mean marine and mammal life would not ingest portions of the other 86% in oceans and landfills
Social commentary on recycling and ocean pollution is growing louder. Consumers are exerting more and more pressure on companies to be responsible. This spells good news for the mutant bug. Companies should be convinced that production costs will lower and corporate responsibility will positively affect their bottom line. When they understand this, creating a new process for recycling plastic water bottles could really take off.