"Making biofuels from renewable resources like glucose has great potential to advance green energy technology," says biochemist Zhen Q. Wang, assistant professor of biological sciences, College of Arts and Sciences. "Glucose is produced by plants through photosynthesis, which turns carbon dioxide (CO2) and water into oxygen and sugar. So the carbon in the glucose — and later the olefins — is actually from carbon dioxide that has been pulled out of the atmosphere.” The research project, led by Wang at UB and Michelle C. Y. Chang at UC Berkeley, marks an advance in efforts to create sustainable biofuels. “We combined what biology can do the best with what chemistry can do the best, and we put them together to create this two-step process. Using this method, we were able to make olefins directly from glucose." Read the news story by Charlotte Hsu.
Published November 30, 2021
It sounds like modern-day alchemy: transforming sugar into hydrocarbons found in gasoline.
But that’s exactly what scientists have done.
In a study in Nature Chemistry, researchers report harnessing the wonders of biology and chemistry to turn glucose (a type of sugar) into olefins (a type of hydrocarbon, and one of several types of molecules that make up gasoline).
The project was led by biochemists Zhen Q. Wang at UB and Michelle C. Y. Chang at the University of California, Berkeley.
The paper, published Nov. 22, marks an advance in efforts to create sustainable biofuels.
Olefins comprise a small percentage of the molecules in gasoline as it’s currently produced, but the process the team developed could likely be adjusted in the future to generate other types of hydrocarbons as well, including some of the other components of gasoline, Wang says. She also notes that olefins have non-fuel applications, as they are used in industrial lubricants and as precursors for making plastics.
To complete the study, the researchers began by feeding glucose to strains of E. coli that don’t pose a danger to human health.
“These microbes are sugar junkies, even worse than our kids,” Wang jokes.
The E. coli in the experiments were genetically engineered to produce a suite of four enzymes that convert glucose into compounds called 3-hydroxy fatty acids. As the bacteria consumed the glucose, they also started to make the fatty acids.
To complete the transformation, the team used a catalyst called niobium pentoxide (Nb2O5) to chop off unwanted parts of the fatty acids in a chemical process, generating the final product: the olefins.
The scientists identified the enzymes and catalyst through trial and error, testing different molecules with properties that lent themselves to the tasks at hand.
“We combined what biology can do the best with what chemistry can do the best, and we put them together to create this two-step process,” says Wang, assistant professor of biological sciences, College of Arts and Sciences. “Using this method, we were able to make olefins directly from glucose.”
“Making biofuels from renewable resources like glucose has great potential to advance green energy technology,” Wang says.
“Glucose is produced by plants through photosynthesis, which turns carbon dioxide (CO2) and water into oxygen and sugar. So the carbon in the glucose — and later the olefins — is actually from carbon dioxide that has been pulled out of the atmosphere,” Wang explains.
More research is needed, however, to understand the benefits of the new method and whether it can be scaled up efficiently for making biofuels or for other purposes. One of the first questions that will need to be answered is how much energy the process of producing the olefins consumes; if the energy cost is too high, the technology would need to be optimized to be practical on an industrial scale.
Scientists are also interested in increasing the yield. Currently, it takes 100 glucose molecules to produce about 8 olefin molecules, Wang says. She would like to improve that ratio, with a focus on coaxing the E. coli to produce more of the 3-hydroxy fatty acids for every gram of glucose consumed.
In addition to Wang and Chang, co-authors of the study include Heng Song at UC Berkeley and Wuhan University in China; Edward J. Koleski, Noritaka Hara and Yejin Min at UC Berkeley; and Dae Sung Park, Gaurav Kumar and Paul J. Dauenhauer at the University of Minnesota. Park is now at the Korea Research Institute of Chemical Technology.
The research was supported by funding from the U.S. National Science Foundation, the Camille and Henry Dreyfus Postdoctoral Program in Environmental Chemistry and the SUNY Research Foundation.
Healing with medicinal plants is as old as humankind itself. Even today, some of the most extensively used drugs such as aspirin, morphine, and quinine are directly extracted from plants. Unlike synthetic drugs, plant natural products are evolutionarily pre-selected chemicals against a wide spectrum of pathogens and other stresses in the environment. However, most plant-based medicines, although biologically effective, have not entered the realm of modern medicine. The biggest challenge is the lack of effective and sustainable methods for producing plant-based medicines because they are present at extremely low concentrations, sometimes less than 0.0001% of fresh weight. The current strategy of farming host plants is unlikely to meet the increasing demand for plant-derived drugs. In addition, these natural products usually have complex chemical structures, and conventional drug synthesis has not been able to produce them in a cost-effective manner.
The long-term goal in my laboratory is to provide alternative solutions for the sustainable and economical production of plant-based medicines through metabolic engineering and synthetic biology. In particular, we build novel metabolic pathways and reroute native pathways in microorganisms such as E. coli and yeast for the production of plant-derived drugs. Our current focus is terpene, the largest family of plant natural products. Many essential medicines including anti-cancer drug paclitaxel, vinblastine, and vincristine, are terpenes or terpene derivatives. Moreover, a complete understanding of biosynthesis pathways in host plants precedes any engineering efforts for scalable production of plant-based medicines. To this end, we are investigating the missing genes in the biosynthesis of digoxin—an important medicine on the World Health Organization’s (WHO) list of essential medicines for the treatment of heart failure. With the unprecedented technological advancement including DNA synthesis, -omics tools, and genome editing in recent years, we hope to tap into the great diversity of plant natural products to benefit the human health."