A team of researchers from Massachusetts Institute of Technology (MIT) have developed a novel way of using yeast to produce ethanol, biodiesel and bioplastics. The research – which was funded by the US Department of Energy and the National Institutes of Health – reduces byproducts from the fermentation process that are often harmful to yeast.
Current biofuels rely almost exclusively on corn – which is not produced in large enough quantities to meet America’s fuel needs. Utilising alternative feedstocks such as yeast (which is much more abundant) opens the door to higher production levels of biofuels in the country.
Feedstocks such as wood and straw need to be broken down into fermentable sugars before they can be used to produce biofuels – a process that in turn releases byproducts toxic to yeast. The University’s new technology targets this problem by improving the yeast cells’ tolerance to the toxins – a tolerance that can be engineered into yeast strains to also provide a possible new source for bioplastics. Using this method, the team showed they were able to improve the ethanol yield of a high-performing strain of yeast by about 80%.
“What we really want to do is open cellulose feedstocks to almost any product and take advantage of the sheer abundance that cellulose offers,” says Felix Lam, an MIT research associate and the lead author of the new study.
High ethanol yields were demonstrated with five different types of feedstocks, such as switchgrass, wheat straw, and corn stover.
“With our engineered strain, you can essentially get maximum cellulosic fermentation from all these feedstocks that are usually very toxic,” Lam says. “The great thing about this is it doesn’t matter if maybe one season your corn residues aren’t that great. You can switch to energy straws, or if you don’t have high availability of straws, you can switch to some sort of pulpy, woody residue.”
“Now we have a tolerance module that you can bolt on to almost any sort of production pathway,” says Gregory Stephanopoulos, the Willard Henry Dow Professor in Chemical Engineering. “Our goal is to extend this technology to other organisms that are better suited for the production of these heavy fuels, like oils, diesel, and jet fuel.”