Saccharification and fermentation of pretreated banana leaf waste for ethanol production

Abstract

The present work reveals the potential applicability of banana leaf waste as feedstock for bioethanol production as very less work has been reported on this feedstock. For achieving the same, the performance of crude cellulases of Aspergillus niger JD-11 is explored for saccharification of untreated and pretreated (alkaline, dilute acid and steam) banana leaf waste. Therefore, to determine the best saccharifying conditions, the effects of various parameters such as enzyme loading (5–15 FPU/g), temperature (40–50 °C), surfactant addition (0.05–0.15% Tween 80 and PEG 6000) and substrate concentrations (2–6%) were studied at 150 rpm and pH 5.0. The crude cellulases yielded maximum reducing sugars (524.83 mg/g) from the dilute acid pretreated banana leaf waste at 45 °C, 15 FPU/g enzyme loading and 2% substrate loading in the presence of 0.15% PEG 6000 (w/v) as surfactant. The fermentation of enzymatic hydrolysate was carried out using initial reducing sugars concentration of 40 g/L in the medium at pH 5.5, 150 rpm and 30 °C for 30 h with the help of Saccharomyces cerevisiae. Ethanol production was estimated at every 6 h and maximum ethanol yield of 0.38 g/g sugar and productivity of 1.28 g/L/h was obtained after 12 h of fermentation of banana leaf waste hydrolysate. Thus, the easily obtained banana leaf waste could be a promising feedstock for bioethanol production.