by Joanna Schroeder (DomesticFuel.com) Scientists from the University of Illinois have reported that they have engineered yeast to consume acetic acid, a previously unwanted byproduct of the process of converting plant leaves, stems and other tissues into biofuels. This innovation increases ethanol yield from lignocellulosic sources (aka second generation feedstocks) by nearly 10 percent. According to researchers, the new advance will streamline the fermentation process and will simplify plant breeding and pretreatment of the cellulose. The results were published in Nature Communications.
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“If we decompose hemicellulose, we obtain xylose and acetic acid,” said University of Illinois food science and human nutrition professor Yong-Su Jin, who led the research with principal investigator Jamie Cate, of the University of California at Berkeley and the Lawrence Berkeley National Laboratory. Jin and Cate are affiliates of the Energy Biosciences Institute (EBI), which funded the research. Jin is an affiliate of the Institute for Genomic Biology at the U of I.
“Xylose is a sugar; we can engineer yeast to ferment xylose,” Jin said. “However, acetic acid is a toxic compound that kills yeast. That is one of the biggest problems in cellulosic ethanol production.”
In an earlier study, graduate student Soo Rin Kim (now an EBI fellow) engineered S. cerevisiae to more efficiently consume xylose. This improved ethanol output, but the process generated an excess of NADH, an electron-transfer molecule that is part of the energy currency of all cells. The buildup of acetic acid also killed off much of the yeast. READ MORE Abstract