Evaluation of different pretreatments for enhanced saccharification of Pinus roxburghii biomass by using mixture of polymerizing enzymes and bioreactor studies for its bioconversion into ethanol

Abstract

This study established a novel pretreatment to overcome recalcitrance of soft wood biomass on substrate morphology, cell wall physical and chemical structures along with the subsequent enzymatic hydrolysis using mixture of cellulase and xylanase enzymes produced by bacterial and fungal cultures. Pine biomass was treated with various combinations of pretreatments viz, NaOH, NaOH+ H2O2, NaOH+ urea, acetone, N- methyl morpholine N-oxide (NMMO). Among all, NaOH+ urea (1:1 each) for 2 h at room temperature was found to be best for saccharification of softwood biomass. SEM micrographs indicated major increase in the wood porosity by the pretreatment, which would confirm increase in the water swelling capacity as well as enzyme adsorption. The analysis of X-ray diffraction showed considerable reduction in the cellulose crystallinity by the pretreatment, sugars so formed from best pretreated substrate was further subjected to fermentation employing separate hydrolysis and fermentation and simultaneous saccahrification and fermentation for ethanol production using mixture of ethanolgens.