Plastic pollution is a global problem that threatens the environment and human health. However, some microorganisms have the ability to break down plastic and use it as a source of energy.
These microbes could potentially help to reduce the amount of plastic waste and recycle it into useful products.
However, most of the known plastic-degrading microbes require high temperatures (above 30°C) to function efficiently.
This limits their industrial applications, as heating the plastic and the microbes would increase the costs and the carbon footprint of the recycling process.
Cold-adapted microbes from alpine and arctic soils
(Photo : MIGUEL MEDINA/AFP via Getty Images)
A team of scientists from Switzerland has discovered 19 novel strains of bacteria and fungi that can digest biodegradable plastics at low temperatures (15°C).
These microbes were isolated from alpine and arctic soils, where they live on plastic litter that has accumulated in these remote regions.
The researchers collected soil samples from Greenland, Svalbard, and Switzerland, and screened them for microbes that could grow on different types of plastic.
They identified 13 genera of bacteria and 10 genera of fungi that showed plastic-degrading activity at 15°C.
The microbes were able to break down polyester-polyurethane (PUR) and two commercially available biodegradable mixtures of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA).
However, none of them could degrade non-biodegradable polyethylene (PE), which is one of the most common plastics in the world.
The researchers used molecular and biochemical techniques to confirm that the microbes were able to chop up the PBAT and PLA polymers into smaller molecules.
They also found that some of the microbes produced enzymes that could catalyze the degradation of plastic.
Also Read: Recycled Plastics Harm Environment by Leaking Hazardous Chemicals, According to Experts
Other examples of plastic-degrading microbes
The discovery of these cold-adapted microbes adds to the growing list of microorganisms that can degrade different types of plastics.
For instance, a bacterium called Ideonella sakaiensis was found to degrade PET by using two enzymes. Another bacterium called Pseudomonas putida was engineered to produce an enzyme that can degrade polyurethane.
Bacteria aren't the only microorganisms evolving to degrade plastic. Isolated from landfill soil, the fungi Trichoderma viride and Aspergillus nomius degraded plastic found in the landfill.
And the marine fungus Zalerion maritimum degraded small pieces of plastic, called microplastics, found throughout the oceans.
Potential applications and challenges
The discovery of these cold-adapted microbes opens up new possibilities for recycling biodegradable plastics at low temperatures. This could save energy and money, as well as reduce the environmental impact of the process.
However, there are still some challenges to overcome before these microbes can be used on a large scale.
For instance, the researchers need to optimize the conditions for their growth and activity, as well as test their efficiency on real-world plastic waste.
Moreover, they need to ensure that the microbes are safe and do not pose any risks to human health or biodiversity.
The researchers also point out that biodegradable plastics are not a perfect solution to the plastic problem, as they still have negative effects on the environment and wildlife.
Therefore, they emphasize the need to reduce the production and consumption of plastic, as well as to improve its collection and disposal.
Related article: The Plastic Paradox
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