Newly Discovered Fungus Capable of Degrading Plastic
Dr. Annika Vaksmaa explores how microbes may offer a solution to reducing plastic waste in the future.
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Humans produce over 380 million tons of plastic every year, and this number is expected to have tripled by 2060. Much of this waste appears in our oceans, and the most abundant type, polyethylene, can be found floating in surface waters and even resting on the seafloor.
In a paper published in Science of The Total Environment, researchers from the Royal Netherlands Institute for Sea Research (NIOZ) reported on the discovery of a fungus capable of breaking down polyethylene particles.
The researchers collected plastic litter from the hotspots of plastic pollution in the North Pacific Ocean, leading to the discovery of the degrader, Parengyodontium album.
Technology Networks spoke to Dr. Annika Vaksmaa, the lead author of the paper, to learn more about how plastic impacts marine life, the discovery of plastic-degrading microbes, and the importance of plastic degraders.
Plastic litter in the ocean has severe and far-reaching effects on marine life. Among many impacts of this pollution, one of the best known is the impact on marine animals that mistake plastic debris for food. When ingested, this plastic can cause malnutrition, blockages and even death. Additionally, other impacts may be due to the toxic additives plastics often contain or compounds absorbed from the water.
Additionally, fish, birds and turtles can become entangled in plastic items such as fishing nets and plastic bags, leading to injuries, impaired movement and sometimes drowning or suffocation. Plastic also contributes to habitat destruction. For example, coral reefs can be smothered by plastic debris, blocking sunlight and hindering their growth, while plastic accumulating on the seabed disrupts the habitats of bottom-dwelling organisms. And counteractively, while it destroys natural habitats, it forms others. This is especially apparent in areas such as the Pacific garbage patch, where organisms that should not be far out from the coast have found new surfaces to attach to and live on.
When plastics are transported in aquatic ecosystems, they can also carry along many species and facilitate the transport of invasive species and pathogens that disrupt local ecosystems.
In addition, as larger plastic items break down, they form microplastics, which are ingested by a wide range of smaller marine organisms. While some studies into the effects of micro and nanoplastics do exist, far more research is needed.
What inspired your attempt to uncover plastic-degrading microbes?
I have always been fascinated by environmental problems such as climate change, which was the subject of my PhD. During this time, I investigated microbes that can oxidize methane. Now, I am focusing more on plastic pollution in the ocean.
I am particularly intrigued by the use of microbes to mitigate environmental issues. The resilience and adaptability of microbes offer a unique and powerful tool for addressing environmental challenges. Discovering and harnessing plastic-degrading microbes can improve the understanding of what happens in nature: which microbes live on plastic, and which can then potentially break it down. In the future, microbes may offer a solution to reducing plastic waste.
How does P. album degrade plastic?
We have now seen that P. album is able to break plastic down, but uncovering how that process happens and which fungal enzymes are involved is another step in this process. It definitely will be worthwhile to identify the molecular mechanisms as this will provide another method of seeking out plastic degraders. If we know the enzymes responsible, we can see which other microbes and their genomes contain these, and from there, we could test if they do break down the plastics as well.
What methods did you use to study the degradation process?
In this study, we used isotopically labeled polyethylene. This is one of the most abundant polymers produced and discarded, so large amounts of it are present in our oceans. Studying the degradation process, which is known to be extremely slow, using these “tagged” plastics enables us to monitor the production of degradation products such as CO2 with very sensitive detection methods.
This allows us to measure plastic degradation in less than a week.
In nature, plastics take decades to break down and many require even longer.
We used nanoscale mass spectrometry for high-resolution imaging and precise chemical analysis. Such methods are crucial for understanding the intricate processes involved in plastic degradation at a very detailed level. However, our results showed that the 13C tag from plastic is mainly found in CO2 and to a lesser extent in biomass, indicating that P. album does not use it for growth.
We also used scanning electron microscopy (SEM) which allowed us to see detailed surface structures and the morphology of biomass at the microscale. This is crucial for understanding how microorganisms and biofilms attach to and interact with surfaces, including plastics.
How important is it to discover other plastic degraders?
Finding other plastic degraders is very important. We now know quite a bit about bacteria and fungi degrading plastics in the terrestrial environment, however it may be that there are other types of microbes and organisms breaking down these hard to break polymers.
Furthermore, as large amounts of plastic end up in our oceans, focusing there and identifying new microbes and pathways can give a holistic understanding and illustrate what happens to the plastics in the marine environment. This can help answer questions on how the break down is facilitated, how the total ecosystem is impacted and the process of biodegradation.
Do you envision P. album could be used to reduce plastic waste industrially?
Microbes are well-known for being used to mitigate pollution and environmental disasters, such as when oil pollution occurs on land. However, further research is required to determine if P. album is the best candidate for plastic degradation on an industrial scale. It is just the first step to identify the organisms, how they function and which plastics can they degrade. To tackle the massive problem of plastic pollution on an industrial scale is something that one hopefully can address in the future. However, the sooner the better, as plastic is still piling up in oceans and the problem is only growing.