How will the new enzyme destroy plastic?

Understanding this mechanism of enzyme activity will pave the way to finding a comprehensive solution to our plastic crisis.

The plastic bottles we throw away daily will last for hundreds of years. That is one of the important reasons why the problem of plastic pollution has become so serious now, when it can cause a deadly impact on variable ecosystems.

But recently scientists have discovered a strain of bacteria that can 'eat' - literally - the plastic used to make bottles, and now they have been improved to speed up. that process. The effects so far are still modest - and even though it is not a perfect solution to plastic pollution, it still shows how bacteria can help create more environmentally friendly recycling measures. .

The plastic bottles we throw away daily will last for hundreds of years.

Unknowingly discovered

Plastics are complex polymer chains, meaning they are very long, consisting of repeated molecular chains that are insoluble in water. The strength of these chains makes the plastic very durable and takes a long time to decompose naturally. If they can be broken down into smaller, soluble molecules, then these newly formed blocks can be collected and recycled into new plastics in a closed loop.

In 2016, Japanese scientists tested another bacterium from a plastic bottle recycling plant and realized that Ideonella sakaiensis 201-F6 could digest the plastic used to make one bottle of water bottles. times, plastic PET (polyethylene terepththalate) . It works by secreting an enzyme (a protein that speeds up chemical reactions) called PETase . This enzyme divides chemical bonds in PET, forming smaller molecules that bacteria can absorb, using carbon in them as a food source.

Even though there are other bacterial enzymes that can slowly digest PET, this new enzyme seems to have evolved specifically for this work. This suggests that it can be done faster and more efficiently, so they have potential for use in biological recycling.

Scientists are trying to understand exactly how PETase works through its structure.

Therefore, a series of research groups are trying to understand exactly how PETase works through its structure. In the past 12 months, groups from South Korea, China, the United States, Britain and Brazil have all published works that show the structure of this enzyme with high resolution and analysis of its mechanism of action.

These studies show that this part of the PETase protein performs a structured chemical digestion process designed to allow it to cling to the PET surface and operate at 30 ^° C, making it consistent with the re-process Processing in biological reactions. Two of the research groups also show that, by cleverly changing the chemical properties of the enzyme, it can interact in a different way with PET, to work faster than natural PETase.

However, the use of microbial enzymes in biological reactions to break down plastics in recycling is still difficult. The physical properties of plastics make them very difficult to interact with enzymes.

PET plastic is used in semi-crystalline structured drinking water bottles, which means that plastic molecules are tightly packed together and enzymes are difficult to penetrate into the deep. The latest research shows that enhanced enzymes can work well, because reactive molecules are very accessible, enabling enzymes to attack more easily, even into the PET molecules hide the deepest.

Modest improvements

But improvements in PETase's operations are negligible, and we still have a way for a solution to our plastic crisis a long way away. But this study helps us understand how this promising enzyme could break PET and suggest ways to do it faster by editing its active parts.

The type of bacteria that can be used for PETase has only recently developed.

Being able to edit enzymes so they can work better than natural growth is relatively unusual. Perhaps this achievement reflects the fact that the bacterium that can use PETase has only recently developed to survive in man-made plastic environments. This can give scientists an interesting opportunity to overcome evolution by editing PETase's optimized features.

Even so, there is still something to worry about. While any bacteria that has been repaired for biological reactions is highly controlled, the fact that they can degrade and consume plastic indicates that the material we are dependent on can not sustainable as we imagine.

If more and more bacteria can eat plastic, then products and structures designed to stand firm for years will face a threat. The plastic industry will face a serious challenge of preventing its products from becoming a prey for hungry microorganisms.

Lessons from antibiotics have taught us that we are always slower than bacteria. But perhaps such studies are allowing one step ahead naturally.