17-08: Development of acetic acid resistant derivates of S. cerevisiae 424A (LNH-ST) for glucose /xylose co-fermentation

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Elizabeth Casey1, Chia-Ling Wu1, Nathan Mosier1, Nancy W. Y. Ho2 and Miroslav Sedlak1, (1)LORRE/Ag. and Bio. Engineering, Purdue University, West Lafayette, IN, (2)LORRE/Chemical Engineering, Purdue University, West Lafayette, IN
Efficient conversion of hemicellulose-derived sugars to ethanol at high yields and titers in the presence of inhibitors generated or released from cellulosic biomass is required for any industry-ready ethanologen.  S. cerevisiae 424A (LNH-ST) developed at Purdue University can efficiently ferment glucose and xylose. Our previous work has shown that acetic acid concentrations and pH under process relevant conditions do not significantly affect glucose fermentation.  However xylose fermentation is significantly affected.  In this poster, we discuss both direct genetic modification and adaptation for the development of an acetic acid resistant derivate of the glucose/xylose co-fermenting S. cerevisiae 424A (LNH-ST). Newly develop strains bearing different modification were tested in flask and 1L fermentor scale for rates and product yields in fermenting xylose or a mixture glucose/xylose in presence of  acetic acid (10 g/L). The ethanol volumetric productivity of the best acetic acid resistant derivate of S. cerevisiae 424A (LNH-ST) was12 fold higher than the original strain in the case of xylose fermentation in flask (8% xylose 1% acetic acid), 1.7 fold higher in the case of glucose/xylose fermentation in flask (12% glucose 8% xylose 1% acetic acid) and 2.9 fold higher in the case of glucose/xylose fermentation at 1Lfermentor scale (12% glucose 8% xylose 1% acetic acid).
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