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Since the 1950s, an estimated 7 billion tons of plastic waste have been generated globally, with roughly 400 million tons added each year. This growing tide of waste has led to the spread of microplastics—tiny plastic particles that have infiltrated water, air, soil, and food, posing potentially significant risks to ecosystems, agriculture, and human health. 

At Cornell University, food scientist Julie Goddard and her research team have embraced this daunting challenge. They’ve engineered variants of a promising enzyme designed to break down microplastics in sewage and wastewater—major conduits for microplastics pollution—with the hope of unlocking an urgently needed water supply for agricultural irrigation.

“As a food scientist, I love the challenge of applications-driven research,” says Goddard, an IFT Fellow and past recipient of IFT’s Outstanding Young Scientist Award in honor of Samuel Cate Prescott. “I love looking at the fundamental hurdles to having something work in a real, complex system and engineering technology to solve them.” In the conversation below, Goddard discusses her team’s research and the potential it holds for creating a more sustainable future.

What got you interested in wastewater? 

As we know, water is an increasingly scarce resource, and we need a lot of it in food and agriculture. The USDA Economic Research Service has reported that approximately 80 percent of consumptive water is used in agricultural irrigation. This is water that is used without a process for replacing it—and it is not a sustainable practice. So, scientists are increasingly looking for alternative irrigation sources. A great one could be treated wastewater. Credit goes to my former doctoral student Hannah Zurier who birthed this idea and to my current doctoral student, Sonia Su, who was recently awarded a USDA predoctoral fellowship to keep the research going.

Talk about the team’s work to make wastewater a viable irrigation source. 

While wastewater holds promising potential, it may be a significant contributor to microplastics. We have engineered an enzyme capable of breaking down plastic in the complex conditions found in sewage sludge. This enzyme targets polyethylene terephthalate (PET), a plastic commonly used in water bottles, food packaging, and textiles—and a major source of microplastics waste. The small, environmentally benign molecules that are products of the enzymatic breakdown of PET can then be used as a carbon source for bacteria. This work builds on a 2016 paper from Japanese scientists that first showed how specialized bacteria could be used to biodegrade plastics as a viable bioremediation strategy. Our specific interest is in adapting this concept to perform well in a system that could have a huge positive impact on food and agriculture.

What results have you seen to date?

So far, the results have been encouraging. We’ve created simulated sludge conditions and bioengineered and tested mutant enzymes in an effort to create an even more effective “PETase,” or enzyme that breaks down polyethylene terephthalate (PET). We’ve been able to come up with one that has more than 17-fold enhanced activity in sludge conditions over those we were originally working with. 

Could this technology eventually be scaled up? 

In food and agriculture, where the margins are super slim, cost-effective scalability is always a question and an important one. The answer I always give is: Your laundry detergent is full of enzymes. For a couple of bucks, you can get yourself a gallon of enzymes. I consider what we do to be applications-driven fundamental research. We’re doing the genetic engineering, the expression, and the characterization with the end use in mind. While I don’t work in R&D, I do have confidence that given how other enzymes have great scalability for low prices, this could likewise be scaled up. 

What message would you leave us with on this topic? 

We cannot continue to feed microplastics into the soil by using contaminated wastewater. It’s bad for the environment and for the known and unknown human health consequences. It also quantifiably adversely affects agricultural production—so it’s an economic issue, too. We have a growing global population that we need to be able to feed, and if we continue to negatively impact our food and agricultural systems, we won’t meet that goal. 

 

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