A comprehensive ligninolytic pre-treatment approach from lignocellulose green biotechnology to produce bio-ethanol

In the present study, we developed a novel ligninolytic enzymes based pre-treatment method for lignocellulosic wheat straw to depolymerize lignin and expose the cellulose polymers to produce bio-ethanol. Wheat straw was pre-treated with ligninolytic enzymes extract produced from Ganoderrna lucidum under optimum solid state fermentation conditions. The pre-treated biomass was further subjected to the enzymatic hydrolysis by the crude unprocessed cellulases (beta-1,4 endoglucanase, 53.5 +/- 1.24 U/mL; beta-1,4 exoglucanase, 41.3 +/- 1.31 U/mL; beta-1,4 glucosidase, 46.8 +/- 1.43 U/mL; and xylanase 39 +/- 2.2 U/mL) produced by Trichoderma harzaianum. Under optimal conditions for enzymatic saccharification, 10% (w/v) of pre-treated biomass was hydrolyzed completely and converted to 72.5 and 2.4 g/L of glucose and xylose, respectively. Initial time screening Sequential Saccharification and Fermentation (SSF) of the concentrated enzymatic hydrolyzate (10%, w/v) by Saccharomyces cerevisiae produced 22.6 g/L ethanol in a fermented medium after 72 h of temperature controlled incubation at 37 degrees C. For maximum ethanol production, different physical and nutritional parameters like pH, temperature, substrate level and inoculum sizes were optimized. Under optimal conditions ethanol production of 33.5 g/L was obtained from ligninolytic treated residual (wheat straw) biomass. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.