Ethanol fermentation from cassava pulp by a novel sequential co-culture

Cassava pulp is a solid waste of the cassava starch factory which contains high amount of starch and cellulose. In this study, the monoculture of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum and co-culture of these two strains were performed at 55°C for 96 h respectively to ferment 4% cassava pulp. After 96 h of culture, the residual glucose in the fermentation broth was 11.96 g/L, 8.02 g/L, and 13.06 g/L for the monoculture of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum and the co-culture, respectively. Saccharomyces cerevisiae was sequentially inoculated into the fermentation broth at 37°C without any nutrient supplementation. After 24 h fermentation, the ethanol concentration of the co-culture system was 8.67 g/L, increasing by 21.43% and 25.83% compared with those of the monoculture of Clostridium thermocellum and Thermoanaerobacterium saccharolyticum, respectively. The results demonstrated the feasibility of ethanol production from cassava pulp without any pre-treatment and enzyme addition by using the novel sequential co-culture.