Plastic waste and access to nutritious food top the list of humanity’s challenges. Yet humans are nothing if not innovative, especially in the face of adversity. Michigan Technological University’s Steve Techtmann, associate professor of biological sciences, aims to convert plastic waste and inedible biomass into edible protein — a biological sleight of hand featuring microbes with a serious hunger.
Techtmann’s groundbreaking research has been awarded the 2021 Future Insight Prize by Merck KGaA, Darmstadt, Germany, a leading science and technology company, along with research collaborator Ting Lu, professor of bioengineering at the University of Illinois Urbana-Champaign.
Using Microbes and Heat to Transform Plastic into Protein
Techtmann is an environmental microbiologist who studies microbial communities in diverse natural environments. His lab studies how complex microbial communities can cooperate to perform functions of industrial interest — in this case, converting waste into safe and edible food while also tackling the issue of plastic pollution.
“We use engineered natural organisms to break down the plastics and non-edible plant biomass to convert into food,” Techtmann said. “It is such an honor to be awarded this prize. This prize will allow us to pursue high-risk and high-reward lines of research that will enable us to move this work forward more quickly.”
The research was initially funded by a Defense Advanced Research Projects Agency (DARPA) cooperative agreement award for $7.2 million over four years to refine a method of chemical and high heat (pyrolysis) deconstruction of plastic waste into protein powder and lubricants. Other researchers working on the project, titled BioPROTEIN (Biological Plastic Reuse by Olefin and Ester Transforming Engineered Isolates and Natural Consortia), are Michigan Tech chemical engineers Rebecca Ong and David Shonnard.
“The foundation of this research greatly benefited from DARPA’s investment,” Techtmann said. “The grant from Merck KGaA, Darmstadt, Germany lets us build off that and enables us to explore other ways to engineer in health benefits by working with probiotics.”
Though Techtmann currently focuses on understanding which microbial communities might be best-suited to the task of transforming the inedible, the project builds on his research into the provenance of microbes by studying their biosignatures in bilge water.
Beyond Garbage In, Garbage Out
The first step in converting plastic and inedible plant wastes to protein powder is to depolymerize the wastes into more biodegradable compounds — that is, break the polymer into its monomers, or individual, components. The current process converts plastic into compounds that look somewhat like oil using heat and a reactor that can deconstruct plastic’s polymer chains. The oil-like compounds are then fed to a community of oil-eating bacteria Techtmann’s lab has been studying. The bacteria flourish on their oily diet, producing more bacterial cells, which are about 55% protein. This lets the team quickly convert plastic to protein.
The researchers envision a system like this: There’s a slot on one side where people throw in plastic waste or non-edible biomass. The waste goes into processing reactors to be broken down by heat. Once broken down, the byproduct is fed into a vat with the bacterial community, which chews on whatever flows there and grows. The cells are then dried down into a powder for later use.
And, as part of the Future Insights prize, the team plans to develop a purely biological process for plastic conversion into food. This process will use enzymes for depolymerizing plastics and include bacteria to break down inedible plant biomass and other wastes.
Supercharged Bacteria to Maximize Nutrition
“Nature has provided us with biological systems for coping with many environmental issues,” Techtmann said. “My role in this project is to identify and grow bacterial communities from the environment that have the ability to use wastes like plastic, as well as discover novel enzymes to break down plastics and other wastes more efficiently.”
At Illinois, Lu focuses on engineering microbial gene circuits for novel chemical and biomolecule production. Working with the team members at Michigan Tech, he aims to engineer bacteria to enrich the protein powder with maximum nutrition — specific amino acids and polyunsaturated fatty acids.
In addition, the research team uses synthetic biology approaches to augment probiotics, improving food quality by increasing nutritional contents, boosting resistance to foodborne pathogens and adding personalized therapeutic benefits.
Thanks to initial funding from DARPA and the newest infusion of both funding and recognition from Merck KGaA, Darmstadt, Germany, Techtmann, Lu and their collaborators will continue to innovate new ways to reduce plastic pollution and bring food to those who need it most.
