Tuesday, April 30, 2013
Exhibit Hall
One major challenge to commercializing cellulosic ethanol is the negative impact of inhibitors on the fermentative performance of industrial microorganisms. Our current, best engineered yeast known as 424A(LNH-ST) has already been used by industry to produce cellulosic ethanol; however acetic acid and ethanol concentration can negatively affect xylose fermentation by this strain. Recently we have developed two derivatives of 424A(LNH-ST), one resistant to acetic acid and the other resistant to ethanol while fermenting xylose. The acetic acid resistant derivate 424A(LNH-ST)-AR has ethanol volumetric productivity from xylose 10 times higher in the presence of acetic compared to the original strain. The ethanol resistant strain, 424A(LNH-ST)-ER, has ethanol volumetric productivity from xylose 14 times higher in the presence of ethanol compared to the original strain. Furthermore, specific xylose consumption rates were observed to be at least two times higher in the absence of inhibitors (acetic acid or ethanol) compared to the original strain. However, the ethanol resistant strain was only slightly resistant to acetic acid. Similarly, the acetic acid resistant strain was only partially resistant to ethanol. In this poster, we compare fermentation capabilities and fermentation parameters of 424A(LNH-ST), 424A(LNH-ST)-AR and 424A(LNH-ST)-ER under different conditions.