We all know plastic is having a detrimental effect on our planet, but to recap - as plastics break down into smaller pieces these manmade polymers permeate into our ecosystems. This is bad because they block animal’s digestive systems and can be small enough to embed themselves in the animal’s skin (Kiprop, 2018) and eventually into the food we eat by travelling up the food chain in a process bioaccumulation. Scientists have been searching for many ways to combat this process and its harmful effects. In 2017, a new strain of the fungus species Aspergillus tubingensis was found the soil around a plastic dumping area in Islamabad, Pakistan. It gained masses of attention from scientists as it was found growing on polyester polyurethane film (PU) (Pinzone, 2017). Researchers found that the fungus was able to degrade a sheet of PU to the point of near dissipation. According to the study abstract ‘after two months in liquid medium, the PU film was totally degraded into smaller pieces,’ (Second Nexus, 2021). This discovery is significant because the fungi can be harnessed by humans to begin the process of bioremediation - the process by which plants and microorganisms combat pollution by converting toxic substances into non-toxic ones (Anwar, 2019).
Polyurethanes plastics have ranging susceptibilities to fungal biodegradation depending on their molecular structure and the position of certain chemical groups (Khan, 2017). As for PU, the fungi is able to secrete enzymes which catalyse the reaction that breaks down the chemical bonds in plastics (urethane bonds). Some of the enzymes found in these fungi include esterase and urethane hydrolase. In many cases, scientists have also detected the presence of an extracellular and membrane-bounded lipase which is most likely responsible for the hydrolysis (breaking down) of the urethane bonds (Khan, 2017). Additionally, the mycelia filaments grown by the fungi are able to further break down the plastic (O’Brien, 2018). We can see this in action through a scanning electron microscope (SEM) which clearly shows the mechanism of the mycelium of Aspergillus tubingensis as it causes ‘surface degradation’ and scarring of the PU (Khan, 2017), allowing the fungus to break down and metabolise the PU.
Bioremediation (or in this context, mycoremediation) is a swiftly growing area of research that scientists are harnessing to use organisms to cheaply and efficiently clean up our planet. This discovery could be of great value to the scientific community and all organisms on Earth. There have been many attempts to reduce plastic usage and waste across the globe. Companies have started producing reusable or recyclable products, clean up missions have just begun in the Great Pacific Garbage Patch and the use of microplastics in products has been restricted. As of now it seems like bioremediation and using Aspergillus tubingensis’ ‘powers’ could be the best direction forward. However, this fungus’ (and possible other species’) ability to digest plastic could have serious repercussions. Plastic’s chemical inertness makes it sterile which is why it is so widely used for food packaging, medical equipment and more. This means that this recently evolved ability of Aspergillus tubingensis could threated the integrity of all plastics which would (literally) damage the structural integrity of our society and the way it functions. The fungus was also spotted in the airways of patients with lung disease, which has severe implications for the commercialisation of the fungus (Second Nexus, 2021) and means much more research must be conducted before this happens. Whilst speculating about the negative repercussions of mycoremediation is important, it can be left to the experts and we can enjoy the fact that their existence might bring a solution to all our plastic problems.
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By Henri and Deeya