The MixAlco process, an example of consolidated bioprocessing (CBP), was utilized for anaerobic fermentation of 80% lime-treated sugarcane bagasse/20% chicken manure at 55 C by a mixed culture of marine microorganisms. NH(4)HCO(3) was recommended by this study to replace CaCO(3) buffer to neutralize the produced carboxylic acids. The resulting ammonium carboxylates can be converted to gasoline or mixed alcohol fuels by downstream processing. Four-stage countercurrent fermentations at various volatile solids loading rates (VSLR) and liquid residence times (LRT) showed the highest acid productivity (1.27 g/(L day)) and highest conversion (76%) occurred at a total acid concentration of 24.4 and 31.3 g/L, respectively. The Continuum Particle Distribution Model (CPDM) predicted the experimental total acid concentrations and conversions within 9.05% and 14.39%, respectively. The CPDM "map" indicates that both high acid concentrations (>50 g/L) and high conversions (>72%) are possible with 300 g substrate/(L liquid) concentration, 30 clays liquid residence time, 5.4 g/(L-day) solid loading rate, and NH(4)HCO(3) buffer. The present study suggests that mixed culture biotechnology in the MixAlco process provides an alternative "carboxylate platform" for biomass conversion. (C) 2009 Elsevier Ltd. All rights reserved.