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Natural sciences
PETstop: Microorganisms in the fight with plastic
A researcher from the NCU knows how to deal with the problem of plastic waste for long. To release microorganisms which can convert almost non-degradable waste into food will do.
PETstop is a biological, environmentally-safe product which accelerates plastic degradation. The fungi it contains are capable of producing hydrolytic enzymes which break hydrogen bonds in materials, which is followed by triggering a wide range of metabolic pathways in order to degrade xenobiotic substances (impurities). Simultaneously, in the first step of colonizing materials, fungi synthesize proteins responsible for their adhesion to plastic, and the complex biological process is initiated.
Prof. NCU, dr. hab. Grażyna Dąbrowska, the Head of the Department of Genetics at the Faculty of Biological and Veterinary Sciences, NCU, Toruń, is the author of this innovative product. Before she declared war on plastic, she had been carrying out long-time research on microorganisms which support the growth of plants studying the ways the microbes affect them.
According to Prof. Dąbrowska, "Functioning of our organisms is coded in our genes, but it is also controlled by microbes creating our microbiome. I knew plants have their co-functioning microorganisms as well. World research has been following this direction. In their studies, scientists, including me, identify and characterize microorganisms originating from plants from the molecular viewpoint. By sequencing, we scientists recognize their genes, analyze their ability to produce phytohormones and other compounds, and thus, based on scientific evidence, we know how it works, why such microorganisms stimulate the growth of plants, protect against pathogens, etc. This is how my adventure with microorganisms started: I wanted to find a biological solution which would reduce the use of chemical fertilizers in farming."
The research was focused on microbes which accompany plants, those which also present the ability to increase the bioavailability of mineral components in soil, and those which cause that plants grow better by absorbing those minerals; moreover, such microbes improve the quality of soil. Noteworthy is the fact that the abovementioned positively influence cost-efficiency of crops.
Concerning the problem with plastic, I was aware of the potential lying behind microorganisms, especially when it comes to those able to grow in anthropogenically degraded, seriously polluted areas." says prof. Dąbrowska. “Omnipresence of plastic was making me terrified, I did not want to observe what was going on in my own house. Plastic caps which we collect and which our kids take to schools within initiatives aimed at helping the disabled turn into kilograms of plastic, and the real image of plastic waste is best discernible when we segregate waste.
The biologist started her work with finding microorganisms which protect plants against pathogens, are capable of existing on some other organism, and exhibit mycoparasitic properties. As it turned out, there exists a big group of such organisms in soil, or even in every kind of environment. The researcher bet on a species of fungi able to live on other fungi.
"Such microorganisms need to produce appropriate enzymes allowing them to decompose and use the host as the source of carbon; additionally, they have to present another molecular potential, namely, to have something that allows them to adhere." explains prof. Dąbrowska. “I started searching for appropriate proteins produced by fungi able to colonize new environments. At present, I am just about to finish my research paper on the fungi which cause plastic degradation, about their genes and proteins, their appearance, and what they form on plastic. It is incredible how microorganisms can adapt to constantly changing environmental conditions. While colonizing plastic, the fungi produce proteins that form a kind of film on its surface. Such forms are called protein biofilms, and the whole PET surface area is covered with proteins that allow those saprophytes to adhere and survive."
Finding microorganisms showing huge potential to produce hydrolytic enzymes (i.e. substances able to cause cell wall degradation) was crucial. The plastic decomposing fungi can also permeate into rape through its roots, thus enabling the development of resistance to pathogens in the plant.
The microorganisms I offer as a biopreparation, their influence on other organisms as well as environment, are thoroughly recognized.
As prof. Dąbrowska comments, "The research is complex, interconnected. Owing to previous studies, selecting the right fungi was not the lucky strike. Before I applied the microorganisms, they had been tested for a long time. I had characterized their properties and checked their ability to live in soils contaminated with metals or of significant salinity. These are pollutants typical of agricultural land. The scope of the research was wide; it took the form of screening tests. Next, I tested thus selected microorganisms on seedlings, I checked their ability to stimulate the plants (and their roots) growth. It is a complex issue, indeed, and it is difficult to imagine the range of the research performed. Still, the microorganisms I offer as a biopreparation, their influence on other organisms as well as environment, are thoroughly recognized. The final step is to find a person or an institution that will trust us and invest in the invention."
For example, local authorities could patronize such an undertaking, although to convince officials is not an easy task. The invention does not give instant results because a lot of time is needed. Prof. Dąbrowska says, "I would believe no one who claims he/she can solve the plastic waste problem on the spot. The world will not deal with the problem within the next few years. I suggest applying an additional preparation on landfill sites, legal or illegal ones. The product would reduce the volume of waste on a site by accelerating degradation. The microorganisms the biopreparation contains function as a sort of inducers which will initiate the plastic degradation process on their own. Additionally, it will enhance the process with the use of other organisms present in soil. If someone believes in the method, we will win."
In order to make sure the process will proceed properly, we need to develop the whole operation scheme. In the fight with plastic, those microorganisms which are capable of colonizing and damaging the material constitute the first front. Next, other organisms are introduced, initially bacteria and soil nematodes, and then lichen, algae, cooperating and biodegradation accelerating plants. Note that the problem of plastic waste is not limited to landfill sites. For example, coated seeds employed in farming contain not only chemicals protecting them against damages but also plastic whose deterioration can also be made faster.
Prof. Dąbrowska tested the product efficiency on the most common polymers, the least degradable PE (polyethylene), PET (polyethylene teraftalate) as well as other biodegradable materials, PLA (polylactic acid) and PCL (polycaprolactone). The innovative PETstop has received a number of Polish and international awards, including the gold medal at the 22nd Moscow International Salon of Inventions and Innovative Technologies “Archimedes 2019", gold medal at the International Invention and Innovation Show INTARG 2019 in Katowice, gold medal at Salon Grand Prix Eiffel de L'invention Innovation Paris, silver medal at the Kaohsiung International Invention and Design EXPO in Taiwan as well as a honorary mention at the iENA International Trade Fair 2018 in Nuremberg. The Polish National Agency for Academic Exchange, NAWA, has chosen this innovative product as one of the 34 inventions to describe in a scientific publication promoting Polish science around the world.
