Simultaneous saccharification and fermentation of delignified lignocellulosic biomass at high solid loadings by a newly isolated thermotolerant Kluyveromyces sp. for ethanol production

Simultaneous saccharification and fermentation studies were carried out using thermotolerant newly isolated Kluyveromyces sp. with three different delignified lignocellulosic biomass viz. rice straw, wheat straw and sugarcane bagasse at 5–15% solid loading and 6–12 FPU g−1 substrate enzyme loading for different time intervals 0–72 h at 42 °C. Maximum ethanol achieved from rice straw, wheat straw and sugarcane bagasse with in-house crude cellulases from Aspergillus terreus was 23.23, 18.29 and 17.91 mg mL−1 at 60 h with 10% solid load and 9 FPU g−1 substrate enzyme loading. Tween 80 1% (v/v) enhanced the ethanol yield by 8.39%, 9.26% and 8.14% in rice straw, wheat straw and sugarcane bagasse, respectively. External supplementation of β-glucosidase to the crude as well commercial cellulases produced maximum theoretical ethanol yield of 71.76%, 63.77%, 57.15% and 84.56%, 72.47%, 70.55% from rice straw, wheat straw and sugarcane bagasse, respectively.