2010 Annual Report 1a.Objectives (from AD-416) To evaluate pretreatment requirements and conversion efficiencies of lignocellulosic feedstocks into fermentation products using mixed culture bioreactors. Develop conversion technologies for conversion of fermentation acids into solvents (i.e., butanol). 1b.Approach (from AD-416) Untreated and pretreated corn fiber will be fed to a mixed culture bioreactor that is optimized for the production of butyric acid. Product butyric acid will then be converted by solventogenic clostridia to produce fuel ethanol. 3.Progress Report The goal of the project is to convert corn fiber into butanol. Corn fiber was successfully pretreated for fermentation at the small pilot-plant scale using a dilute-acid catalyst. The hydrolysate was readily converted to butyric acid using a mixed culture fermentation. Selectivity for butyric acid formation was increased by inhibiting methane formation and by operating with a more dilute feed concentration, so, as to avoid butyric acid toxicity. The conversion of butyric acid into butanol was demonstrated for a continuous system that incorporated in situ butanol recovery. The Authorized Departmental Officer's Designated Representative monitored the activities of this agreement via e-mail contacts.