The plastic bottles we fled today are still standing on the earth even hundreds of years later. The ever-accumulating plastics have caused extremely serious pollution problems, and the ecological damage caused by it is shocking. For example, many organisms in the ocean are precisely because of them. Existed and faced death threats.
In recent years, scientists have discovered that strains that can truly feed on plastics, and continue to improve these strains to improve their operational efficiency through the use of protein engineering and protein evolution.
Plastic is a complex and water-insoluble polymer with a long repeating molecular chain. The strength of these long molecular chains makes plastics a very durable material that takes a long time to be naturally degraded. By breaking them down into smaller soluble chemical units, new plastics can be formed in closed-loop systems by collecting and recycling these basic units.
In 2016, Japanese scientists tested different bacteria from plastic bottle recycling plants and found that Ideonella sakaiensis 201-F6 could digest the plastic used to make disposable beverage bottles - PET (polyethylene terephthalate). Bacteria secrete an enzyme called PETase that breaks certain chemical bonds (esters) in PET, leaving those smaller molecules absorbed by bacteria and using the carbon in the molecule as food. source.
Although we also know that there are other bacterial enzymes that can slowly digest PET, the new enzyme apparently appears to be dedicated to this work. It decomposes the plastic more quickly and efficiently, and has The potential of the cycle.
Therefore, several research teams have been trying to understand how it works by studying the structure of PETase. In the past year, teams from China, Korea, the United Kingdom, the United States, and Brazil have all published high-resolution enzyme structures and related Mechanism analysis papers. These papers show that the part of the PETase protein that performs the chemical digestion binds to the surface of the PET and operates at 30°C, allowing it to be recycled in the bioreactor. Nevertheless, in the bioreactor The idea of using bacterial enzymes to decompose and recycle plastics is still a matter of course. The physical properties of plastics make them less likely to interact with enzymes.
The PET used to make beverage bottles has a semi-crystalline structure, so the plastic molecules are very tightly packed together, making the enzyme difficult to contact. The latest research shows that the modified enzyme is likely to have very strong efficacy because of the reaction involved That part of the molecule has a strong contact ability, able to direct even the PET molecules that have been masked.
It is actually quite unusual to want to artificially modify an enzyme to make it more productive than when it is in its natural state. Perhaps the result of this research reflects the fact that bacteria have recently evolved to survive. The ability to use PETase against man-made plastics. Perhaps scientists can transcend natural evolution by engineering the optimization of PETases. But there is also a worrying problem: Although any modified bacteria used in bioreactors may be subject to height Control, but its ability to evolve into plastics that can be degraded and consumed may mean that the plastic we rely on so much may not be as durable as we think.
If there are more bacteria that can eat plastic in nature, those plastic products or building structures that were originally designed to remain for many years will be threatened. By then, the plastics industry will face severe challenges to prevent plastic products from being contaminated by hungry microbes. .