An ordinary plastic bottle, such as those found in any supermarket, takes up to 1,000 years to completely degrade. A container made of polyethylene terephthalate, a relatively common plastic, takes between 450 and 1,000 years to decompose in landfills. Finally, a polyethylene plastic bottle can last anywhere from 10 to 1,000 years, depending on its thickness and the environmental conditions to which it’s exposed.
These numbers reflect something undeniable: The plastics we use daily are a pollutant worth considering. Moreover, they don’t degrade completely. Instead of returning their basic components to the environment and becoming part of the natural recycling chain, they fragment into microplastics and remain in this state for many years. It’s a nuisance, no doubt about it.
“Living” Plastics Are Already Here
Fortunately, we have other less polluting materials, such as paper, which can perfectly replace plastic in some situations. However, there are different scenarios where replacing the plastics I mentioned in the first paragraph takes work. But there’s hope. Scientists at the Chinese Academy of Sciences, led by synthetic biologist Chenwang Tang, have developed a new type of plastic that can self-destruct in less than a month when discarded.
It sounds really good, right? Moreover, the technology they’ve fine-tuned to develop this new type of plastic is genuinely innovative. In 2016, technicians at a recycling plant in Japan discovered a bacterium that naturally produces a protein capable of rapidly degrading plastic. Since then, several research groups have found other bacteria that produce enzymes capable of consuming plastic, spurring labs to produce synthetic enzymes that degrade even faster.
These scientists have found a way to incorporate bacteria spores that produce plastic-degrading enzymes into the structure of the plastic itself.
The Chinese scientists led by Tang have found a way to incorporate bacteria spores that produce plastic-degrading enzymes into the very structure of a type of plastic known as polycaprolactone (PCL). So, when the plastic decomposes after use, these enzymes are released and consume the plastic entirely. However, this strategy has a problem: These enzymes are unstable and fragile.
Fortunately, the Chinese research group doesn’t seem to give up easily. To solve the problem, they decided to modify a gene from the Burkholderia cepacia (BC) bacterium to promote the production of an enzyme resistant to elevated temperatures and pressures. Problem solved. As the surface of the plastic degrades, the spores are released and accelerate the degradation of the PCL molecules, which disappear almost completely.
One of the most apparent benefits of this technology is that it eliminates the need for antibiotics to accelerate plastic degradation. We can only hope that the scientists’ proposal will make it out of the laboratory and succeed when tested in the demanding conditions of the real world. Let’s keep our fingers crossed.
More info | Nature Chemical Biology
Image | Catherine Sheila
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