Cellulosic ethanol has shown promise as a feasible alternative fuel, especially if the hydrolysis of lignocellulosic biomass is done through a single step process known as consolidated bioprocessing (CBP). A major challenge for CBP, especially for large-scale industrial applications is the inhibition of celluloytic microorganisms by ethanol. While recombinant DNA technology and microbial acclimatization by exposure have resulted in some increase in ethanol tolerance, the search remains for robust bacteria that can proliferate in industrially-relevant conditions. This study applied an anaerobic gradient system to provide a continous spatial pathway for the selection of cellulolytic consortia with increased tolerance to ethanol. DGGE analysis showed that increasing concentrations of ethanol impacts the community profile. Biofilm formation of cellulose degrading communities has been found to be influenced by species diversity. Environmental gradients have shown promise for selective enrichment of cellulolytic consortia at desired conditions required for industrial application.