Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Third generation strategies for improved bioethanol formation center on the use of microbes to conduct consolidated bioprocessing. Conventional processing of lignocellulosic biomass employs hot acid pretreatment (HAP). When diluted, this material mimics the natural habitat of extremely thermoacidophilic archaea. We are developing a consolidated bioprocessing platform based on the engineering of extreme thermoacidophiles. Components of the system include directed evolution for pretreatment compatibility, hydrolytic enzyme reconstruction for rapid deconvolution, and metabolic redesign for optimum saccharification. However, a primary constraint of HAP is the formation of toxins such as furfural and related pentose dehydration products that constrain microbial growth. This poster presents progress towards an additional component of the new platform concerning the engineering of tolerance to these toxins. Sulfolobus solfataricus encodes 13 thermostable alcohol dehydrogenases. In prior studies (Friest JACS 132:5930), the SsADH10 isozyme exhibited broad preference towards unnatural compounds. New studies indicated cell lines harboring modulated levels of one isozyme revealed a strong correlation between toxin lethality and enzyme abundance. Additional studies explored the dependence of this property on other isozymes as well as on diverse biomass-derived toxins and intermediates. These data inform ongoing efforts for further development of the consolidated bioprocessing technology.