6-28: Fractionation of Conditioned Corn Stover Hydrolysates and Inhibition of Ethanologen Growth and Fermentation

Although many of the inhibitory compounds of pre-treated corn stover hydrolysate have been identified, our understanding of hydrolysate toxicity is still incomplete.  By using solid phase extraction techniques to separate hydrolysates into fractions based on their polarity, we tested fractions for toxicity using a quantitative high-throughput microbial growth assay as well as fermentation with Zymomonas mobilis 8b as the model organism.  Detailed analysis of the chemical composition of the different fractions allows us to differentiate the toxic effects from various compound classes and also provides an opportunity to examine the contribution of unknown compounds to overall toxicity.  By using the tools developed in our laboratory for quantifying hydrolysate toxicity under a variety of pretreatment and conditioning processes we may eventually identify those conditions that are favorable for fermentation organisms and provide critical feedback for selecting and optimizing the pretreatment process for biomass to ethanol conversion.