【Frontiers in HaiChuan Chemical Technology】Fungi used in research at the Kunming Institute of Botany, Chinese Academy of Sciences, “eat” plastic particles

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In everyday life, plastic is everywhere: from shopping bags to delivery packaging. While it brings convenience to our lives, it also causes serious pollution problems. In recent years, the impact of plastic waste on the ecological environment has become a focus of global concern. For a long time, researchers at the Mountain Future Research Center of the Kunming Institute of Botany, Chinese Academy of Sciences (hereinafter referred to as the \"Mountain Center of the Kunming Institute of Botany\") have conducted in-depth studies on the ecological and environmental effects as well as the metabolic fate of plastic waste in the \"plants–soil\" system, achieving a series of new advancements. The relevant findings were published in the international journals “Journal of Hazardous Materials” and “International Biodegradation and Biodecomposition”. “These achievements enable us to understand plastic pollution more clearly and also provide new approaches to addressing this issue. ”Xu Jianchu, a researcher at the Kunming Institute of Botany, explained. Small-sized microplastics are highly harmful. Plastic waste gradually breaks down in the environment into tiny particles, namely microplastics. Today, microplastic pollution is almost everywhere – in the oceans, on land, in the atmosphere – and even the remote Tibetan Plateau has not been spared. “Moreover, in agricultural production, microplastics can enter the ‘plant-soil’ system through various forms of agricultural management practices and plant uptake. ”Dr. Shahid Iqbal from the Kunming Institute of Botany explained that it was not previously clear what ecological effects different types and sizes of microplastics would have in this system. To this end, researchers at the Mountain Center of the Kunming Institute of Botany conducted a field experiment to specifically study the effects of microplastics of different particle sizes and types on the corn-soil system. They chose polyethylene and polystyrene microplastics with particle sizes of 75 micrometers, 150 micrometers, and 300 micrometers for the experiments. “The experimental results are concerning. ”Shahid Iqbal said that studies have found that polyethylene microplastics with the smallest particle size of 75 micrometers cause the most severe damage to soil and crops. It reduced the levels of organic carbon and organic nitrogen in the soil by 1%–1.5%. At the same time, carbon dioxide emissions per kilogram of soil increased by 88.55 milligrams, while nitrous oxide emissions rose by 1.01 milligrams per kilogram, resulting in a 177% increase in the soil’s global warming potential. Not only that, but in terms of crop growth, corn treated with 75-micron polyethylene microplastics showed a 48% decrease in seed germination rate, a 30-cm reduction in plant height, and a halving of biomass and grain yield. “At the same mass, microplastics with smaller particle sizes have a larger surface area compared to those with larger particle sizes; as a result, they have a greater contact area with soil microbes and nutrients. This leads to more severe carbon and nitrogen loss as well as enhanced catalytic effects. ”Li Yunju, a researcher at the Kunming Institute of Botany, explained. “For the first time, this study confirms at the field scale that microplastic pollution may exacerbate the impacts of global change through a positive feedback mechanism involving ‘soil-crop-climate’. ”Xu Jianchu said that as large-particle microplastics in the environment gradually degrade into smaller particles, ecological risks will continue to increase. Exploring new approaches to pollution control: In addition to studying the hazards posed by microplastics, researchers are also focusing on the fate of different types of plastic pollutants within the \"plant-soil\" system, that is, the issue of biodegradation of plastics. “Plastic pollution poses a serious threat to the ecological environment; traditional treatment methods are not efficient, and the potential of microbial degradation has not yet been fully utilized. ”Gui Heng, an associate researcher at the Kunming Institute of Botany, said that the research team continuously tried to identify microfungi capable of degrading plastics from various \"plant-soil\" environments, and focused their attention on a fungus known as \"Trichoderma iranense\". “During the 60-day fungal cultivation experiment, we continuously monitored the weight loss, molecular weight changes, and surface morphology changes of different plastics. ”Gui Heng explained that they also used untargeted metabolomics to analyze the differential metabolites produced when the fungi were exposed to polyurethane and polyethylene, and to examine the activity of key enzymes. The experimental results show that this fungus has a significant effect on the degradation of polyurethane; within 60 days, it was able to reduce the weight of the polyurethane film by 11.05% and its molecular weight by 19.10%. Their research not only reveals the molecular mechanisms by which fungi degrade plastics, but also provides a theoretical basis and potential targets for the development of fungus-based microbial remediation techniques, offering a \"nature-based solution\" to alleviate the global plastic pollution crisis. “Through ongoing research, we have seen, on the one hand, the harms of microplastics in the ‘plant–soil’ system ； On the other hand, new approaches to addressing plastic pollution using scientific methods have also been found. ”Xu Jianchu said that in the future, the team will continue to conduct in-depth research to further explore the changes that occur during the long-term aging of microplastics.