Lignocellulosic biomass is a renewable resource with the potential to significantly reduce our dependence on petroleum. However, its recalcitrant nature necessitates robust conversion technologies to enable its conversion into carbon neutral fuels and products. Co-solvent Enhanced Lignocellulosic Fractionation (CELF) employs tetrahydrofuran in solution with aqueous dilute acid to fractionate biomass into its major components. The solids produced by CELF are highly amenable to saccharification, however, the higher enzyme loadings required to achieve high rates along with high yields are cost prohibitive. Anaerobic organisms that combine enzyme production and fermentation in a single unit operation called consolidated bioprocessing (CBP) can eliminate separate enzyme production and thereby dramatically reduce process costs. This thesis reports on understanding factors that influence the performance of CELF pretreatment of lignocellulosic biomass with subsequent CBP to maximize product yields at low process severity. Results show that CELF and CBP synergistically deconstructed hardwood Poplar, eliminating the need for external enzymes, with CELF-CBP pairing enabling ~100% glucan solubilization by C. thermocellum of solids produced by operation of CELF at a low process severity (2.87). GPC and NMR characterization of residual lignin showed decreases in average molecular weight and a substantial decrease in β-O-4 linkage both after CELF and CELF-CBP, suggesting further lignin modification by C. thermocellum CBP. CELF-CBP (C. thermocellum) pairing was then compared with CELF-fungal cellulase Ctec2 and CELF-C. thermocellum secretome combinations. Fractal kinetics were applied to model glucan solubilization rates by each of these three systems, and the rate coefficient kt and fractal exponent h were compared. Residual xylan from CELF was shown to inhibit C. thermocellum activity at high solids loadings (75-100 g/L). However, using T. thermosaccharolyticum in combination with C. thermocellum in a co-culture strategy minimized xylose accumulation and increased glucan solubilization to >97% at 75g/L solids loadings. The CELF process was then optimized for renewable ester biosynthesis using an appropriately engineered C. thermocellum. In addition, CELF pulping of industrial hemp enabled utilization of whole hemp as hemp-fuel and hemp-crete. Finally, aminating lignin from the CELF process was demonstrated to produce an excellent absorbent for toxic dyes. These results demonstrate the versatility of CELF technology and advantageous CELF-CBP synergies for utilization of recalcitrant biomass for production of renewable fuels and other bioproducts.
