There is a kind of bacteria that can eat plastic as delicious

[China Packaging News] The plastic bottles we throw away today will stand on the ground even after hundreds of years. The accumulation of plastics has caused extremely serious pollution problems and shocked the ecological damage. For example, many organisms in the ocean are facing death threats because of their existence.

In recent years, scientists have discovered strains that can really feed on plastics. Through the use of protein engineering and protein evolution, these strains have been continuously improved to improve their operational efficiency.

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. If they can be broken down into smaller soluble chemical units, then 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 PET ( polyethylene terephthalate ) , the plastic used to make disposable beverage bottles . The bacteria can secrete an enzyme called PETase , and this enzyme can break certain chemical bonds ( esters ) in PET , leaving those smaller molecules to be absorbed by the bacteria, and the carbon in the molecule As a food source.

Although we also know that there are other bacterial enzymes that can slowly digest PET , the new enzyme apparently seems to have been specifically created for this work. It can decompose plastic faster and more efficiently, and has the potential for biological circulation.

Therefore, several research teams have been trying to understand the working principle of PETase by studying its structure. In the past year, teams from China, South Korea, the United Kingdom, the United States, and Brazil have published papers on the structure and related mechanism analysis of enzymes at high resolution. These papers show that the part of the PETase protein that performs chemical digestion will bind to the surface of PET and operate at 30 ° C , allowing it to be recycled in the bioreactor. Nonetheless, the idea of ​​using bacterial enzymes to decompose and recycle plastics in bioreactors is still a matter of knowing. The physical properties of plastics make it difficult for them to interact with enzymes.

The PET used to make beverage bottles has a semi-crystalline structure, so the plastic molecules are packed very closely together, making it difficult for enzymes to contact. The latest research shows that the improved enzyme is likely to have a very strong effect, because the part of the molecule involved in the reaction has a strong contact ability and can directly hit the PET molecule that is covered .

It is actually very unusual to want to artificially modify the enzyme to make it work more efficiently than it does in its natural state. Perhaps this research reflects the fact that in order to survive, bacteria have recently evolved the ability to use PETase against artificial plastics. Perhaps scientists can go beyond natural evolution by optimizing the form of PETase by engineering . But there are also a cause for concern: Although any improved over the bioreactor using bacteria are likely to be highly controlled, but it can evolve into plastic degradation and depletion of this capacity may mean - we are so dependent on The plastics may not be as durable as we think.

If there are more bacteria that can eat plastics in nature, then those plastic products or building structures that were originally designed to last for many years will be threatened. By that time, the plastics industry will face severe challenges in order to prevent plastic products from being contaminated by hungry microorganisms.