(470c) Improvement of Biofuel Production By Fungal Pretreatment and Periodic Flushing System

In this study we investigated the fermentation performance (quantified by solvent and acid production) of fungal pretreated (Phanerochaete chrysosporium) agricultural residues (corn stover or miscanthus).   The fermentation process employs sequential cultivation of the cellulolytic bacterium Clostridium thermocellum (C. thermocellum) at 65 ^oC followed by the cultivation of the butanol-producing strain, Clostridium beijerinckii (C. beijerinckii) at 35 ^oC. Pretreated agricultural residues were fermented in a glass column fitted with porous polyethylene discs at the base of the column, allowing periodical flushing of the column with culture medium while retaining the solid substrate. The hypothesis of this study is that fungal pretreatment improves cellulose hydrolysis and the repeated flushing process helps relieve the metabolic inhibition which occurs in high- solid substrate fermentation.  Time profiles of soluble sugars, solvents and acids were quantified during the entire culture process.  A parallel study quantifying the efficacy of reinoculation of C. thermocellum or C. beijerinckii on product generation was performed to optimize the repeated flush process.