Plastic pollution and food security are two of the biggest problems of our time. That’s why American researchers are trying to use the first problem to help solve the second. Their solution: tasty cookies made from plastic bottles and agricultural waste like corn stalks.
After going through a stage of chemical processing, these materials are fed to genetically modified yeast that converts them into proteins and other food raw materials, researchers said at the American Chemical Society conference.
The study was carried out as part of a NASA research program focused on producing food in the enclosed environments of future deep space missions.
“We were trying to develop technologies to recycle plastics so we could produce higher-value products. So we thought: why not focus on producing food? After all, plastic is made of carbon, just like food,” said Lahiru Jayakody, associate professor at Southern Illinois University Carbondale, in a press release.
He said his team is now waiting for university approval to test the experimental cookies.
Chemical Factories
Yeast and other microbes have been used for years as chemical factories to produce medicines and other molecules. Insulin, for example, is no longer isolated from animal pancreases but is instead synthesized by yeast inside large bioreactors.
Using CRISPR, the revolutionary gene-editing technology whose discovery won a Nobel Prize in 2020, Jayakody and his colleagues engineered yeast strains that metabolize molecules from plastics and agricultural waste, converting them into proteins, fats, vitamins and flavor compounds.
The main raw material is PET (polyethylene terephthalate), a polymer widely used in clear plastic bottles, which was mixed with dried corn stalks and leaves.
This mixture underwent “oxidative hydrothermal dissolution,” a technique that uses water and oxygen at high temperature and pressure to break down raw materials into smaller molecules.
Those molecules are then fed to the genetically modified yeast, which converts them into edible substances. The researchers added plant fiber, starch and sweeteners to these substances and used a 3D printer to “print” cookies, which they named mBites.
The taste of cookies made from plastic, the researchers said, can be further improved using other genetically modified yeast strains that produce vanilla flavor from biomass, or other strains that convert PET’s ethylene glycol into beta-carotene, the pigment that gives carrots their color and that the human body converts into vitamin A.
“We’re using microorganisms to turn the cookie into a more appealing and consumer-friendly product,” Jayakody said.
He also expressed optimism that mBites could be ready for consumption within a few years and could be used not just on Earth but in extreme environments like submarines, or even future colonies on Mars and the Moon.
“Global food demand is expected to grow by 35 to 56 percent by 2050, while roughly 30 percent of the world’s population could face hunger in the future. I believe the way to address this challenge is by putting microorganisms to work,” the researcher said.
Not everyone shares his optimism, though. Commenting on the study in New Scientist, Jason Hallett of Imperial College London said he sees no commercial future for mBites.
“We produce 400 million tonnes of plastic waste a year. We’re not going to turn all of that into cookies,” he said.
