Investigation of the potential of agro-industrial material as low cost substrate for ethanol production by using Candida tropicalis and Zymomonas mobilis

Ethanol production from agro-industrial waste (thippi) was analyzed as low-cost feedstock using mixed culture fermentation. Reducing sugars yield by acid hydrolysis was 395.2 g kg−1 thippi and ethanol yield was 35.8 g kg−1 thippi. However, reducing sugars in enzyme hydrolysis was 535.33 g kg−1 thippi, which resulted in 254.45 g ethanol yield kg−1 thippi (72.8 g l−1, using mixed culture), revealed 93.18% of the theoretical yield of ethanol. Zymomonas mobilis alone yielded 228.55 g ethanol kg−1 thippi (65.3 g l−1), which is 82.83% of the theoretical yield and Candida tropicalis alone yielded 214.2 g ethanol kg−1 thippi (61.2 g ethanol l−1), reaching more than the published value for C. tropicalis with starch. This is 76.58% of the theoretical yield. These data are of 1 l fermentor. Ethanol fermentation from thippi hydrolysate was then scaled up to 10 l fermentor; ethanol yield was 219.63 g kg−1 thippi, which was 78.82% of the theoretical yield.