The conversion of lignocellulosic biomass to biofuels has shown the difficulties in the efficient enzymatic hydrolysis of cellulose due to its recalcitrant and complex structure. The pretreatment of biomass is required to alter or remove the structural barriers and make cellulose more susceptible to enzymatic hydrolysis. Mixed hardwood was pretreated with liquid hot water at different severities ranged between log Ro = 3.05 and 4.41 solubilizing ~80% of the initial hemicellulose. However, the pretreated hardwood retained almost 80-90% of the lignin that is initially present which may play an inhibitory role on the enzymatic hydrolysis of cellulose. Lignin is hypothesized to hinder the action of the cellulases on cellulose by forming a physical barrier or non-productive binding of the enzymes. In order to understand the changes of lignin properties during liquid hot water pretreatment and its interactions with enzymes, lignins were isolated from pretreated hardwoods using extensive enzymatic hydrolysis and protease treatment. We measured changes in chemical structure of the lignin using fourier transform infrared spectroscopy (FTIR) analysis, glass transition temperature (Tg), and enzyme hydrolysis of cellulose. Our results showed the non-productive binding of enzymes to lignin, hence compromising enzyme activity.

Changes in lignin properties during liquid hot water pretreatment and its role on enzymatic hydrolysis

246th National Meeting (2013)

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