Microbes Can Transform Plastic Trash Into Edible Protein

What if we could solve a portion of the plastic pollution crisis by turning harmful waste into nutritious food? 

While that might sound like something out of a 21st-century fairy tale—and certainly doesn't replace the need to make less plastic to begin with—it’s a fantasy that science could actually make real: German science and technology company Merck KGaA awarded their 2021 Future Insight Prize last month to two researchers who developed a process for using microbes to transform plastic waste into protein.  

“The winners of this year’s Future Insight Prize have created a ground-breaking technology with the potential to generate a safe and sustainable source of food while reducing the environmental harms associated with plastic waste and traditional agricultural methods,” Belén Garijo, chair of the executive board and CEO of Merck KGaA, Darmstadt, Germany, said in an announcement. “We congratulate Ting Lu and Stephen Techtmann for their promising research, and hope that the Future Insight Prize will help to accelerate their efforts.”

Plastic into Food 

Lu, professor of Bioengineering at the University of Illinois Urbana-Champaign, and Techtmann, associate professor of Biological Sciences at Michigan Technological University, began working on the idea in September of last year with their research teams at the two universities. Initially, the project was prompted by a call from funding-body the Defense Advanced Research Projects Agency for “interesting and creative ways to deal with wastes,” Techtmann tells Treehugger. 

But the researchers also had more personal motivations. 

“I’ve been to underdeveloped, rural areas where farmers work hard yet cannot put enough food on their table,” Lu writes to Treehugger in an email. “This left a lasting impression on me of the food shortage crisis. Years ago, I came across a U.N. report, I was shocked by the population of hungry people and saw an urgency for food generation. When I started my own lab at Illinois, I wanted to work on something intellectually challenging and yet societally impactful. Food generation is such a topic, and I am super excited to tackle that.”

Essentially, the process that the researchers devised first uses chemicals to break down plastic polymers and then uses naturally occurring microbes to convert the plastic building blocks into microbial biomass that has nutritional value.

“The key concept underlying our project is transformation, a process that converts one form of material to another,” Lu explains. “In this case, we transform plastic waste to food.” 

The beginning and the end product might seem like “radically different” materials, Lu acknowledges, but from a chemical perspective, they are not as different as one might expect. Plastic and food both contain the essential building blocks of carbon, oxygen, and hydrogen. The chemical formula for PET, the kind of plastic used for water bottles, is (C10H8O4)n, while the formula for wheat flour is C6H10O5)n. 

The process doesn’t generate flour, exactly. Instead, the end result is what Techtmann calls “microbial cells.”

“Microbial cells are made up of very similar things to the food that we eat right now,” Techtmann tells Treehugger, especially when it comes to plant products. They contain proteins, lipids, and vitamins. 

These cells currently take the form of a powder that could itself be a food product, Ting writes. That powder could also be used to make energy bars or other types of food. 

Scaling Up

The concept is still at the level of what Techtmann calls “bench scale experiments.” Right now, the researchers can only convert 0.87 to 1.75 ounces (25 to 50 grams) of plastic at a time. However, one promising fact is that the process is remarkably efficient. It is able to change 75% to 90% of HDPE plastics into potentially edible cells. 

In the shorter term, Techtmann says the researchers hope to unify the components of their plastic-to-food process into a single device that could be used as a tool for disaster relief. 

“Often food and clean water are something that is needed in a disaster scenario, and you often have excess waste,” he explains. 

But Techtmann and Lu’s ambitions aim further still. 

“Our long-term goal is to develop a plastic degradation and conversion technology that is versatile and efficient, and can be utilized at large scale, which ultimately helps to address both plastic pollution and food insecurity, two grand challenges of our modern society,” Lu writes.

He hopes the food it generates will be a legitimate alternative food source for humans, as well as potentially for livestock, cats, and dogs. 

“I really think that there are different possibilities,” Lu says.

Future Insight Prize 

Winning the Future Insight Prize 2021 will help them realize these goals. The prize was launched in 2019 in honor of Merck KGaA’s 350th anniversary. Winning is more than symbolic: the honor comes with a $1.18 million (1 million Euro) stipend that the company plans to give out annually for the next 35 years. 

“With the Future Insight™ prize, we aim to empower researchers tackling some of humanity’s most pressing global challenges in health, nutrition, and energy,” Garijo says on the prize website. 

To that end, every year the company seeks nominations around a particular theme: In 2019 it was pandemic preparation, in 2020 drug resistance, and in 2021 food generator. The 2022 theme will be carbon dioxide conversion. 

Techtmann says that the initial nomination for the prize “was a surprise to us.” 

“It’s an amazing honor,” he adds. “It’s exciting to see that this company . . .is willing to put a substantial investment to try to address some of these major challenges that are faced by society and to see the work that we’re doing as potentially a step in helping society is pretty amazing.”

Merck’s investment also has practical implications for the researchers. It will enable them to fund more graduate students and postdocs to assist with the project’s development and make immediate improvements. 

“The prize is incredible, because it offers resources and encouragement for us to advance the research,” Lu agrees. “While we have generated promising results, there is still a long way to go from concept demonstration to real-world applications.” 

Some of the immediate improvements that researchers want to make include:

1. Increasing the efficiency of the transformation
2. Improving and assuring the safety of the final food product
3. Enhancing the nutrition of the food by, for example, figuring out how to make polyunsaturated fatty acids
4. Expanding to new types of waste, such as non-edible plant matter

“With the prize, we can pursue high-risk, high-return ideas that are potentially transformative,” Lu writes.