Winter 2017
Illustration by Harriet Lee Merrion

From orange peels to yoga pants

University researchers aim to turn agricultural waste into everyday products

Kechun Zhang was working on his doctoral thesis at the California Institute of Technology in 2007 when he realized that biotechnology could potentially help treat disease and solve global challenges such as environmental destruction and climate change. So he took things a step further, doing post-doctoral work at the University of California Los Angeles, where he learned how to engineer biochemical reactions in living cells in order to make useful products from plant-derived sugar.

Now a 2015-17 McKnight Land Grant Professor in the University of Minnesota’s College of Science and Engineering, Zhang has expanded his research. And in 2016, he and his colleagues announced groundbreaking findings that could change the way we produce many everyday products, making them more affordable, sustainable, and environmentally friendly.

In collaboration with other U of M researchers and students, Zhang has engineered a new synthetic biopathway that efficiently and cost-effectively uses sugars derived from inedible agricultural waste—such as orange peels, cornstalks, and sugar beet pulp—in the manufacturing of spandex, foam, stents, 3-D printing materials, medications, chewing gum, biofuels, and nutrients and flavor enhancers in human and animal foods.

“By engineering cells, we are able to make a new material that is biodegradable, cost-competitive, and high-performance.”
Kechun Zhang

To develop the pathway, they genetically modified bacteria so they could more affordably produce DOP, a key chemical used in spandex and other products. The new pathway allows reactions to happen faster than with the current conversion process and yields higher carbon conversion.

Zhang’s findings, which were published in the February 2016 issue of Nature Chemical Biology, are significant because scientists have long sought more sustainable sources of the raw materials needed to make many common products in order to reduce our reliance on petroleum-based plastics.

Additionally, the current use of corn and sugarcane for manufacturing and fuel is considered controversial because it affects the food supply and can drive up prices.

“This study is one of only a few involving the construction of artificial metabolic pathways so far,” says Zhang, who is also a researcher in the National Science Foundation’s Center for Sustainable Polymers, located on the Twin Cities campus.

Zhang’s work is supported by the National Science Foundation and the university. He credits his McKnight Land Grant Professorship and the 3M Non-Tenured Faculty Award with allowing him the freedom to develop the new biosynthetic pathway and significantly expand the list of bioengineered products that could potentially be produced and on the market in the next few years. 

“Current biodegradable polymers don’t match the performance of petroleum-based polymers,” he says. “By engineering cells, we are able to make a new material that is biodegradable, cost-competitive, and high-performance.”

Eye on the future

Soon after his first article was published, Zhang and his colleagues, including Regents Professor Frank Bates and chemistry professor Marc Hillmyer, published related research in the Proceedings of the National Academy of Sciences of the United States of America. In that article, they describe their work as “rewiring” bacteria to transform plant-derived sugar into a molecule that can be converted to produce plastic and elastic materials. “Everything is made of sugar or sugar-derived materials,” Zhang explains. “Plants turn carbon dioxide into sugar, and it’s fed into all of life.”

Together, the three investigators formed Valerian Materials, a U of M startup that manufactures high-performance, biodegradable plastics from renewable resources for a variety of applications. Their hope is to see the new, sustainable materials they are developing take the place of non-renewable, nonbiodegradable polymers.

“Petroleum is the source of most commodity chemicals and materials, so the petrochemical industry is essential to our modern quality of life,” Zhang says. “The fossil-based economy is reaching a turning point as a consequence of accelerated petroleum consumption, environmental pollution, and climate change.”

By employing synthetic biology to design and evolve novel metabolic pathways in “industrial workhorses” like yeast and E. coli, Zhang says he hopes to pave the way to bio-based production of chemicals that are not found naturally “but could potentially address certain energy and environmental challenges.”

Meleah Maynard is a Minneapolis writer and editor.