Tuesday, April 20, 2010
11-59

Transcriptomic analysis of the effect of acetic acid on S. cerevisiae 424A(LNH-ST) during the co-fermentation of glucose and xylose

Elizabeth Casey1, Miroslav Sedlak1, Nancy W. Y. Ho2, and Nathan S. Mosier1. (1) LORRE/Ag. and Bio. Engineering, Purdue University, 500 Central Dr., West Lafayette, IN 47907, (2) LORRE/Chemical Engineering, Purdue University, 500 Central Dr, West Lafayette, IN 47907

Lignocellulosic biomass is a promising renewable feedstock for the microbial production of chemicals and fuels, especially ethanol.  Processing lignocellulose for biofuel production results in the release of the major fermentable sugars glucose and xylose.  However, the primary processing steps required for this conversion also produce a range of compounds that can inhibit the subsequent microbial fermentation.  One such inhibitory compound is acetic acid, liberated from hemicelluloses during the pretreatment of the biomass.  We previously reported acetic acid to be inhibitory to cell growth, substrate consumption (especially xylose), and ethanol productivity, and stimulatory to the metabolic yield of ethanol.  To further explore the effect of acetic acid on a cellular level, a genome-wide analysis of gene expression levels over the course of a batch co-fermentation of glucose and xylose was conducted using microarray technology.  RNA samples were extracted for analysis from S. cerevisiae 424A(LNH-ST) at various time points throughout the co-fermentation of glucose and xylose with either 0 or 10 g/L acetic acid at a controlled pH of 5.5.  In this poster, we report the results of this transciptomic analysis, focusing on genes that are identified as differentially expressed when cells are inhibited by acetic acid. 

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