The world is struggling for a solution duplication plastic waste occupying the planet. It is not an easy task, because it is a plague far from diminishing, growing at a rapid rate of several tens of millions of tons each year. Find a system to reduce this waste (usually, germs) is the goal of many scientists, and in fact, some experiments are starting to show results. One of the most promising trials is this year’s one by the Swiss Federal Institute WSL.
In recent years, several types of microorganisms that can process plastic have been discovered. But, The main obstacle is the high temperatures required by these microorganisms. normally above 30ºC to perform said operation.
This limitation not only increases economic costs, but also makes it difficult to achieve a carbon neutral solution.
However, scientists have now discovered that Some cold-adapted microbes have enzymes that can work at very low temperatures.thus making things easier.
Researchers from the Swiss Federal Institute WSL ctheir trials entered the mountain ranges of the Alps and also the polar regions, where they find microorganisms that can break down plastics at cooler temperatures. In an article published in the journal Boundaries in Microbiology This explains the potential for cold-adapted microbes to revolutionize the plastic recycling industry.
Studies reveal that these organisms are found in the Alps and the Arctic. They can decompose biodegradable plastics at 15ºC, significantly reducing the economic cost and environmental impact. of the enzymatic recycling process as described by the work’s principal investigator, Joel Rüthi.
It was determined that the bacterial strains belonged to 13 genera within the bacterial species by culturing the isolated microbes in a single strain using molecular techniques in the laboratory environment, under dark conditions and at 15 °C. phylum Actinobacteria And proteobacteria. They can be classified into 10 genera within these families.
They succeeded in breaking down biodegradable plastic
Then, through a series of tests, the ability of each was evaluated for its ability to digest three different materials: non-biodegradable polyethylene (PE), biodegradable polyester-polyurethane (PUR), and commercially available biodegradable terephthalate blends. adipate (PBAT) and polylactic acid (PLA).
Although none of the strains were able to digest PE after 126 days of incubation, 56% of the strains consisting of 11 fungi and eight bacteria were able to degrade PUR at 15°C. In addition, 14 fungi and three bacteria were found that can digest plastic mixtures of PBAT and PLA.
A nuclear magnetic resonance (NMR) and fluorescence-based assay confirmed that these strains could break down PBAT and PLA polymers into smaller molecules.
“It was very surprising for us to find this. most of the tested strains were able to degrade at least one of the tested plastics. The most effective organisms were two uncharacterized fungal species belonging to the genera Neodevriesia and Lachnellula, which were able to digest all plastics tested except PE,” explained Rüthi.
“Interestingly, we noticed that the ability to break down plastic was dependent on the culture medium for most of the strains, and each reacted differently to the four environments tested,” added the scientist.
Beat Frey, WSL Senior Scientist and Group Leader, who is also a researcher, explained: “Microbes have been shown to produce a wide variety of polymer-degrading enzymes that are involved in the breakdown of plant cell walls.”
Although the study focused on digestion at 15 °C, The optimal temperature at which the enzymes of successful strains work has not yet been determined.. Most strains tested can grow well between 4°C and 20°C, with an optimum around 15°C.
The next challenge is to identify specific plastic-degrading enzymes. It is produced by microbial strains and optimizes the process to obtain large amounts of protein.
The scientists speculate that further modification of enzymes may be necessary to improve properties such as stability, which will ultimately lead to the development of environmentally friendly and cost-effective plastic recycling methods.
Reference work: https://www.frontiersin.org/articles/10.3389/fmicb.2023.1178474/full
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