Abstract:
This research work is to assess the conversion of cassava peels to bioethanol using a co-culture of Aspergillus niger and Saccharomyces cerevisiae in a simultaneous saccharification and fermentation process. Aspergillus niger was isolated from soil at the cassava processing factory while Saccharomyces cerevisiae was isolated from palm wine. The cassava peels were sorted, washed, sun-dried, and milled. Aspergillus niger and Saccharomyces cerevisiae were inoculated into the fermentation medium containing the ground cassava peels under a proper laboratory condition, and kept at room temperature for the fermentation process to occur. A similar experimental setup was done with only Aspergillus niger being inoculated into the fermentation medium for the determination of the rate of hydrolysis of the ground cassava peels. Before the inoculation of either Aspergillus niger or Saccharomyces cerevisiae, the concentration of reducing sugar in the fermentation broth was 1.608 mg/ml. After inoculation, the concentration of reducing sugar in the fermentation broth containing only Aspergillus niger was 6.084 mg/ml, 8.148 mg/ml, 11.930 mg/ml, 27.606 mg/ml, and 31.150 mg/ml for days 1, 2, 3, 4 and 5 respectively while the concentration of reducing sugar in the fermentation broth containing a co-culture of Aspergillus niger and Saccharomyces cerevisiae was 3.815 mg/ml, 4.488 mg/ml, 3.206 mg/ml, 6.160 mg/ml, and 5.246 mg/ml for days 1, 2, 3, 4, and 5 respectively. The average percentage yield of bioethanol (v/v) in the fermentation broth containing a co-culture of Aspergillus niger and Saccharomyces cerevisiae was 1.5%, 2.167%, 2.167%, 3.333%, and 4.167% for days 1, 2, 3, 4, and 5 respectively. The result of this research shows that sugars released from the hydrolysis of cassava peels by Aspergillus niger can be fermented to bioethanol by Saccharomyces cerevisiae when both microorganisms exist in the same system.
