Ethanol production from lignocellulosic substrate Prosopis juliflora

Delignification of Prosopis juliflora at 10 g, 100 g and 1 kg level at 1:10 ratio using 2% (w/v) Na2S2O4 at 30 ± 2 °C for 18 h resulted in removal of 82.16 ± 0.34%, 81.82 ± 0.36% and 79.23 ± 0.25% of lignin, respectively. By subsequent biphasic dilute acid hydrolysis of substrate, 51.4 ± 0.47%, 51.2 ± 0.52% and 48.1 ± 0.18% of holocellulose was hydrolyzed with release of 1.94 ± 0.03 g/L, 2.16 ± 0.10 g/L and 1.68 ± 0.05 g/L phenolics and 1.17 ± 0.02 g/L, 1.10 ± 0.03 g/L and 1.07 ± 0.04 g/L of furans, respectively. Later, detoxification of hydrolysates removed 85.83 ± 2.8% of phenolics, 87.85 ± 2.4% of furans with sugar loss of 4.74 ± 0.12%. Enzymatic hydrolysis of substrate yielded 39.37 ± 0.92 g/L, 37.37 ± 0.8 g/L and 30.07 ± 0.48 g/L of sugars, respectively. Further, fermentation of mixture of acid and enzyme hydrolysate at 100 g level of substrate using co culture-c (Saccharomyces cerevisiae VS3 and Pichia stipitis NCIM 3498) produced 10.85 g/L of ethanol with fermentation efficiency, ethanol yield and productivity of 87.34 ± 0.28%, 0.445 ± 1.32 g/g and 0.301 ± 0.011 g/L/h, respectively.