Bio-ethanol production from Elephant grass using co-cultures of Aspergillus niger and Saccharomyces cerevisiae in simultaneous saccharification and fermentation

Elephant grass (Pennisetum purpureum) was evaluated for its ethanol production potential using co-cultures of Aspergillus niger and Saccharomyces cerevisiae. Proximate and lignocellulose analysis carried out on the plant sample showed that it had crude fibre, lignin, hemicellulose and cellulose contents of 31.5%, 26.78%, 18.76% and 34.16% respectively. A. niger strain (AN-15) used for the simultaneous saccharification and fermentation (SSF) of the plant sample was isolated from soil and selected upon subsequent screening because it gave highest yield of cellulase enzyme (0.1792 IU/ml/min). S. cerevisiae strain (PW-4) used for the SSF was isolated from palm wine and selected upon subsequent screening after showing ability to assimilate more sugars compared to other isolates. Fermentation of plant sample was carried out at different substrate concentrations ranging from 2-10% and highest ethanol yield (1.68g/100ml) was observed at 6% substrate concentration though lesser than that observed for glucose at same concentration (8.38g/100ml). Optimization of culture parameters for ethanol production showed maximum ethanol yield at pH 5, 35oC and agitation rate of 300 rpm.