New yeast strain could help deliver biofuels from non-food plant matter
04 June 2015
Researchers have developed a revolutionary strain of yeast that could help significantly accelerate the development of biofuels from non-food plant matter.
The approach, developed by researchers at Biofuels pioneer Mascoma LLC and the US Department of Energy's BioEnergy Science Centre (BESC), could provide a pathway to eventual expansion of biofuels production beyond the current output limited to ethanol derived from corn.
Their 'C5 FUEL' 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 June 3 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," says BESC director, Paul Gilna.
"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," says Gilna. "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 utilise 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.
The next step for BESC will be to demonstrate and again validate the application of the consolidated bioprocessing approach using thermophilic, or heat-loving, bacteria to produce biofuels directly from biomass in a single process.