Bacteria fight plastic waste: This is how microbes break down plastic

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Plastic waste is a problem, and it’s getting worse. The plastic that ends up in the environment breaks down only very slowly, if at all. They break down into microplastics that accumulate in soil, lakes, rivers and in our food. Microplastics even float in the atmosphere and are distributed on the ground in the form of raindrops or snowflakes.

Therefore, it is important to avoid waste. But any process that removes this persistent waste from the environment is also welcome. There has long been a way to break down plastic with the help of microorganisms, using enzymes to break down the polymer into its individual parts, the monomers. These monomers can then be used to create new plastics. Such microorganisms are known, including from Swiss research, but they are usually tested at temperatures above 30°C.

Bacteria multiply on plastic

Now, a team of researchers from Northwestern University in Illinois has revealed the mechanisms by which a specific group of bacteria breaks down and feeds on plastic. these as Comamomonadaceae Bacteria are known to thrive on plastic found in urban waterways and sewage systems, but until now it wasn't clear exactly how these microorganisms “eat” the plastic. According to lead author Ludmilla Aristilde, in the study published in the journal Environmental Science and Technology, the research team is the first to systematically describe how wastewater bacteria Comamonas testosterone Plastic materials can be absorbed, broken down, broken down and used as a carbon source.

three step process

It's a three-step process: In the first step, bacteria break down the plastic into small pieces called nanoplastics. They then secrete a special enzyme, a protein, that acts as a biocatalyst and further breaks down these nanoplastics into rings of carbon atoms. Finally, bacteria use these carbon rings as a food source. These small components provide a source of bioavailable carbon that bacteria can use for their own growth and development.

“Astonishingly, this bacterium is able to complete the entire process, and we have identified a key enzyme responsible for the breakdown of plastic materials,” Ari Stilde, an environmental engineer at Northwestern University, said in a statement. The new The study builds on Aristide's previous work on its mechanism. Comamonas testosterone Enables simple carbohydrates produced by the breakdown of plants and plastics to be metabolized.

Focus on PET

C. Testosterone Polyethylene terephthalate (PET) is a plastic commonly used in food packaging and beverage bottles. PET is known for its resistance to degradation, which makes it a significant source of plastic pollution. According to Aristilde, PET plastic accounts for approximately 12% of total global plastic consumption, and the proportion of microplastics in wastewater is as high as 50%. Aristide therefore stressed that the study of these bacteria is important for understanding and solving the problem of plastic waste.

to interact C. Testosterone To better understand plastics, Aristide and her team used a variety of theoretical and experimental methods. First, they grew bacteria on PET films and particles and observed changes on the surface of the plastic material. They also analyzed the water surrounding the bacteria and looked for evidence of nanoplastic degradation. Finally, the scientists also examined the insides of the bacteria to determine the tools they use to break down PET. They examined all the enzymes within the cells and were able to identify specific enzymes that were activated when the bacteria came into contact with PET plastic.

In fact, it is this enzyme that breaks down the PET polymer into its monomers, a fact that was demonstrated in another experiment: Working with Oak Ridge National Laboratory in Tennessee, the researchers developed a system that could not express this enzyme. bacterial strains. The ability of these bacteria to break down plastic is significantly reduced.

Bacteria produce nanoplastics

Aristide explains that wastewater is a huge reservoir of microplastics and nanoplastics. Many people assume that these particles enter the purification system in their final state, but research shows that nanoplastics can also be produced through the activity of bacteria during wastewater treatment. As Aristilde highlights, these bacteria use plastic from wastewater treatment plants to produce nanoplastics, but are unable to “eat” all the plastic produced. Some of it is released from wastewater treatment plants into receiving waters and ends up in lakes or oceans. Environmental engineers stress that the issue must be addressed next.