Evaluation of pretreatment methods for enzymatic saccharification of wheat straw for bioethanol production

Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. The current study is focused on two different pretreatment methods of wheat straw using mild temperatures (100 °C for 2 h and RT for overnight). In one method, native substrate was treated with 1.5% (w/v) NaOH at two different above mentioned conditions followed by acid hydrolysis (0.75% (v/v) sulfuric acid at 100 °C for 2 h). In another method, the native substrate was initially treated with acid (0.75% (v/v) sulfuric acid at 100 °C for 2 h) followed by treatment with 1.5% (w/v) NaOH at two different above conditions. After the pretreatments, the residues were treated with Accellerase 1500 (26 U/g) and maximum yield of glucose (65.2 g L−1) were found with 0.75% sulfuric acid (100 °C for 2 h) followed by alkali (1.5% NaOH at 100 °C for 2 h). Fermentation of this hydrolyzate using Saccharomyces cerevisiae strain produced 24.4 g L−1 of ethanol with corresponding yield of 0.44 g/g.