When established by the U.S. Department of Energy in 2007, BESC sought researchers from institutions across the United States to bring breadth and depth of expertise to the challenge of overcoming biomass recalcitrance. Transformative advances in understanding recalcitrance require detailed knowledge of the chemical and physical properties of biomass that influence its resistance to degradation. Research has been aimed at determining:
- How these properties can be altered by engineering plant biosynthetic pathways.
- How biomass properties change during pretreatment.
- How such changes affect biomass-biocatalyst interactions during deconstruction by enzymes and microorganisms.
Historically, the term “recalcitrance” was coined to describe an overall phenotypic trait of biomass, namely the degree of difficulty in obtaining access to sugars complexed in the plant cell wall. However, based on new knowledge about cell wall chemistry, structure, and biochemistry, BESC researchers have redefined recalcitrance as a phenomenon in terms of pathways and interactions, both in cell wall formation and bioconversion. This increasing knowledge of the scientific basis of recalcitrance underpins the overall BESC goal of eliminating it as an economic barrier to cost-effective biofuel production.
BioEnergy Science Center (BESC) research articles from Innovation Toronto
Biofuels pioneer Mascoma LLC and the Department of Energy’s BioEnergy Science Center have developed a revolutionary strain of yeast that could help significantly accelerate the development of biofuels from nonfood plant matter.
The approach could provide a pathway to eventual expansion of biofuels production beyond the current output limited to ethanol derived from corn.
C5 FUEL™, engineered by researchers at Mascoma and BESC, features fermentation and ethanol yields that set a new standard for conversion of biomass sugars from pretreated corn stover—the non-edible portion of corn crops such as the stalk—converting up to 97 percent of the plant sugars into fuel.
Researchers announced that while conventional yeast leaves more than one-third of the biomass sugars unused in the form of xylose, Mascoma’s C5 FUEL™ efficiently converts this xylose into ethanol, and it accomplishes this feat in less than 48 hours. The finding was presented today at the 31st International Fuel Ethanol Workshop in Minneapolis.
“The ability to partner the combined expertise at Mascoma and BESC in engineering microbes to release and convert sugars from lignocellulosic biomass has greatly accelerated the translation of basic research outcomes to a commercial product,” BESC Director Paul Gilna said.
Gilna noted that this success and continued efforts through BESC could go a long way toward reducing the cost of ethanol and growing the number of commercial-level ethanol production plants. A key focus of BESC is to use basic research capabilities and expertise to validate the consolidated bioprocessing approach to improve cost competitiveness.
“Driving down the cost to develop, verify and consolidate bioprocessing was at the heart of the BESC effort when we began in 2007, and this achievement allows us to advance to the next challenge,” Gilna said. “This accomplishment represents a clearly impactful example of how our partnering with industry can accelerate the translation of our research capabilities and findings into commercial products.”
Although cellulosic biomass such as corn stover, wheat straw and bagasse (the fibrous remains after sugar is extracted from sugarcane or sorghum) is abundant and cheap, because of recalcitrance — a plant’s resistance to releasing sugars for conversion to alcohol – it is much more difficult to utilize than corn. However, Mascoma’s new strain of yeast, which is one of many strains Mascoma developed as part of BESC over the last two years, proved highly effective at xylose conversion.
While most processing methods simply convert cellulose to sugar, this new approach also converts hemicellulose, which significantly increases overall sugar yield and thereby increases the level of ethanol produced. In fact, the new strain of yeast simultaneously yields 97 percent conversion of xylose and glucose—and does so in a significantly shorter period of time than existing approaches.