A mixed culture formed by Cellulomonas flavigena and Xanthomonas sp. was able to grow in continuous culture in a medium with sugar cane bagasse as carbon source without additional growth factors. The effect of temperature, pH and dilution rate (D) upon the microbial population ratio and biomass composition was studied. Both microorganisms co-existed between 30 and 40 degrees C, at pH 5.8-7.0 and D=0.04-0.11 h(-1).