WORCESTER, Mass. – Discoveries in the stomachs of termites and other organisms are helping a team at Worcester Polytechnic Institute’s Life Sciences and Bioengineering Center develop technology for the next-generation of plant-based biofuels.
Corn-based ethanol is now the primary biofuel produced in the United States. It’s made by converting the starch from corn kernels into sugar, which is then fermented, much in the same way as beer or wine, to produce ethanol. A team at WPI is now working on ways to develop biofuels that are based on cellulose, which makes up the heavy, woody fibers found in all plants. “We need to develop biofuels that do not compete with the food supply,” said Alex DiIorio, PhD., assistant professor of biology and biotechnology and director of WPI’s Bioprocessing Center at Gateway Park. “The goal is to find a renewable source of liquid fuel that is better for the environment, that doesn’t rely on crude oil, and that doesn’t affect the price of food.”
The biofuels work in DiIorio’s lab is sponsored by California-based EdenIQ, which is investing heavily in the development of cellulosic ethanol. “With the early success in the discovery of new organisms, our program with WPI is being renewed for another year,” said Glenn Richards, PhD., vice president of technology at EdenIQ.
Cellulose makes up the tough fibers that give plants their shape and strength—it is the most abundant plant material on the planet. Cellulosic ethanol can be made from any plant material, including what is now considered agricultural waste, such as plant stalks, wood chips, corn cobs, and similar materials. It can also be made from many plants that grow on lands not suitable for farming.
The problem, however, is that it is much tougher to break down cellulose fibers to release their sugar than it is to extract sugar from corn kernels. So far, processes to make cellulosic ethanol have proven too expensive and too complex for industrial scale fuel production. That’s where the WPI team has focused its efforts and made some discoveries. “We need to find better methods for breaking down those woody fibers,” DiIorio said. “And when it comes to digesting wood, termites know how to do that pretty well.”
Last year, DiIorio’s team went into the field and took samples of organisms they found in places where trees and plants were decaying. They began to analyze the arsenal of bacteria found in termite guts and other organisms that secrete enzymes that break up cellulose, freeing glucose (sugar) that the organisms then use for nutrition. After months of testing and analysis, DiIorio’s team identified approximately 100 types of bacteria, including many novel strains not previously characterized, that appear critical for breaking up the cellulose. “From the initial 100 we screened, we’ve identified 10 organisms that look very promising,” DiIorio said. “Now, in phase two of this project, we’ll focus on those 10, to see if we can optimize them for larger scale production.”
Extracting sugar from cellulose is the first important step in the process, but to produce liquid biofuel the sugar needs to be fermented into ethanol. That’s where Reeta Prusty Rao, PhD., assistant professor of biology and biotechnology at WPI, is focusing some of her lab’s work. Once again, the idea is to leverage nature’s abilities. “Nature has done much of the work for us, by giving us Saccharomyces cerevisiae, which is commonly called Brewer’s Yeast or Baker’s yeast,” Prusty Rao said. “It’s the same yeast people have been using for thousands of years to brew beer; it would be wonderful if we could get it to brew fuel.”
Using Brewer’s Yeast is an efficient way to ferment alcohol, but it has limitations when fermenting ethanol. High concentrations of ethanol eventually become toxic for the yeast. Prusty Rao, who is also working on a sponsored research program with EdenIQ, is exploring ways to adapt yeast strains so they are more resistant to ethanol, and thereby able to ferment higher concentrations of the fuel, making for a more economic and scalable process. “The company has a propriety strain of yeast that they have asked us to work with, to see if we can optimize its capabilities,” Prusty Rao said.
Prusty Rao’s lab is interested in understanding the molecular and genetic basis of fungal diseases, working in yeast as a model organism. The ultimate research goal is to identify unique fungal genes as potential targets for antifungal agents, of which few are currently known. Her expertise with yeast, however, led to the collaboration with EdenIQ, because of the necessity of fermentation in the production of ethanol.
