Human activity has more and more impact on the environment, there is no doubt about that.
Despite the fact that social awareness regarding the use of plastics, their recycling and the damage they cause in nature is increasing, the harsh reality is that we still have many aspects to improve in order to turn the tables. Will we find an alternative?
Earthworms: masters of recycling
Earthworms – known to all for those rainy days when we could see them in our childhood – are true “masters of recycling”.
Due to their ability to degrade organic matter and recycle nutrients in the soil, they have become true allies of human beings for the production of different types of products, among which natural compost stands out. A result of the digestive process of these annelids.
Previous studies had already shown that, in addition to their already amazing powers for the degradation of organic matter – as if it were turning water into wine -, worms have the ability to degrade plastic. This has made them an ideal model for studying the impact of these materials on living organisms.
A new study published in the journal Environmental Science & Technology of the American Chemical Society has been based on this last aspect. In it, a group of researchers has verified the ability of earthworms to digest synthetic and biodegradable plastics , evaluating their preference and trying to analyze their impact on these animals.
Floor cleaners and plastic eaters
In their day-to-day life in the underground world, worms live by digging up the ground and consuming everything in their path. Among the components that can be found are microplastics derived from pollution from larger plastic waste.
Earthworms are capable of breaking down these microplastics into much smaller fragments. However, their eating behavior in relation to the type of plastic they consume and the consequences that these compounds (or the toxic substances they release) may have for their body were still unknown.
To study it, the researchers placed worms in different chambers that were exposed to soils with different types of biodegradable and synthetic plastics. In the test, they observed that these invertebrates were attracted to soils containing mainly two types of plastics. On the one hand, particles of polylactic acid (PAT), a type of biodegradable plastic, or, on the other hand, particles of polyethylene terephthalate (PET), a type of synthetic plastic derived from petroleum.
In a subsequent analysis, the researchers exposed the worms to lactic acid and terephthalic acid, components of PLA and PET, respectively, which give off a bad smell. With this, the researchers verified that the worms were attracted, which indicated that a possible cause of their feeding behavior was the smell of both types of plastic.
Digestion depends on plastic
In another of the experiments, the researchers placed the worms in a soil containing a mixture of biodegradable plastic (PLA) and synthetic (PET).
Analyzing animal waste, they found that they were able to break down biodegradable plastic into smaller fragments than synthetic plastic.
In addition, another important observation they made is that the digestion of biodegradable plastic was slower, an aspect that, in future research, the group wants to continue studying to check the effects it may have on the health of earthworms and the potential of these invertebrates. to get rid of biodegradable plastics.
Living Organisms: An Environmental Alternative?
Earthworms, despite their degrading abilities, are not the only animal that we know of with the ability to consume plastic and that are considered as a possible option to eliminate them from the environment. Already in 2017, a study was published in which they verified that the larva of the wax moth ( Galleria mellonella ) is an excellent polyethylene eater.
In addition to animals, there are also organisms such as bacteria, fungi, algae and even plants that, in recent times, have shown the ability to metabolize and degrade, not only plastics, but also other types of pollutants.
These studies focus on one of the branches of biotechnology known as bioremediation, thanks to which, using living organisms and even enzymes derived from some of them, important advances are being made to rid the environment of contaminants that cause a significant impact such as hydrocarbons, organochlorines or heavy metals, among others.
Despite these possible alternatives… What is our role? Prevent or remedy?
Bombelli, P., Howe, CJ, & Bertocchini, F. 2017. Polyethylene bio-degradation by caterpillars of the wax moth Galleria mellonella. Current Biology.Wang, L. 2022. Earthworms’ Degradable Bioplastic Diet of Polylactic Acid: Easy to Break Down and Slow to Excrete. Environmental Science & Technology.