Straw-to-bioethanol potential from Sake yeast

New processes to turn agricultural waste into biofuel could result from research at the University of East Anglia — and the key is a series of yeast strains related to those that make Japan’s traditional drink, Sake. These processes could help relieve pressure on agricultural land by using straw, corncobs and sawdust to make bioethanol, rather than using land that could be used to grow food for crops to turn into fuel.

It’s currently very difficult to turn cellulose-rich agricultural waste into biofuel. The cellulose has to be turned into as form which can be fermented, which requires heat and acidic conditions. But this makes breakdown products related to compounds called furfurals, which are toxic to yeast. Genetically-modified yeasts have been designed to withstand these compounds, but the Easst Anglia team has now identified yeast strains which are naturally tolerant to furfurals.

Working with the Institute for Food Research and its National Collection of Yeast Cultures, Tom Claske and colleagues from East Anglia’s School of Biological Sciences identified five natural yeasts that could resist furfurals. The best of these, S. cerevisiae NCYC 3451, produced the highest ethanol yield and is genetically related to the yeast used to ferment rice into Sake. ‘These  strains represent good candidates for further research, development and use in bioethanol production,’ said Clarke, who describes the research in the journal Biotechnology for Biofuels.