There are over 5 billion tons of plastic waste accumulated across the planet, much of which are microplastics that may harm human health and pose a long-term threat to agricultural productivity and food security. The gargantuan task of cleaning up this pollution could be aided by a tiny protein: a specialized enzyme designed to break down plastics into simple components that natural bacteria in the environment can use as a food source.
Julie Goddard, professor of food science, and her research team are engineering a unique enzyme that targets polyethylene terephthalate (PET), a common plastic used in packaging and textiles. Her lab has successfully engineered a new enzyme capable of breaking down plastic in the complex conditions found in sewage sludge, and she envisions a system in which these enzymes could someday help reduce microplastics in treated wastewater. Microorganisms are regularly used in wastewater treatment. This work was inspired by former graduate student Hannah Zurier, Ph.D. ’22, now a postdoctoral research scientist at Columbia University, and continues with doctoral candidate Sonia Su, Goddard said.
Wastewater treatment plants are a major source of microplastic pollution into the environment – and into agricultural fields. To avoid overuse of freshwater resources, and in recognition of growing global water scarcity, treated wastewater effluent is increasingly being used for agricultural irrigation. Although there is more public attention on microplastic pollution in oceans than in soils, far more microplastics are released into soils each year: four to 23 times as much.
“Wastewater reuse is an important strategy in the global fight against water scarcity, but it demands that the wastewater is free of contaminants, including microplastics,” Goddard said.
“When microplastic-contaminated wastewater is used for irrigation, microplastics will accumulate in the soil, and that has a significant impact on agricultural productivity.”
Microplastics – defined as plastic particles 5 mm or smaller – harm agriculture in myriad ways. They limit soil microorganisms’ movement and access to nutrients, which in turn disrupts the microbes’ critical role in soil nutrient cycling necessary for plant development. Microplastics in soil are absorbed directly into plants’ seeds, roots and vascular systems, disrupting their ability to uptake water and nutrients, and passing through to the animals and humans who consume them.
