(175j) Cellulase Adsorption on Sugarcane Bagasse Lignin at 30 and 45°C

Extents of adsorption of cellulolytic enzymes on lignin, derived from sugarcane bagasse, were found to be an inverse function of incubation temperature. Lignin derived from acid hydrolyzed liquid hot water pretreated bagasse completely adsorbed cellulolytic enzymes from Trichoderma reesei at 45°C within 90 min. In comparison, lignin derived from enzyme hydrolyzed liquid hot water pretreated bagasse adsorbed only 60% of the enzyme when initial loadings were 50 mg protein/ g dry lignin. Activities adsorbed were endoglucanase, exoglucanase and β-glucosidase activities. At 30 °C, adsorption of all of the enzymes was minimal while enzyme hydrolysis at 30 °C approached that at 45 °C after 168 h. Hence, temperature provided a direct approach for decreasing loss of enzyme activity since enzyme adsorption on lignin was decreased. The time-dependent adsorption time courses showed a significant difference in the relationship between enzymes adsorption on lignin residues that were derived through different extraction methods, i.e., acid and enzyme hydrolysis. These observations help to explain why simultaneous saccharification and fermentation (SSF) and consolidated bioprocessing (CBP), both carried out at 30–32 °C, offer viable options for mitigating lignin-derived inhibition effects, and result in significant ethanol titers, even though a suboptimal temperature for enzyme hydrolysis is used.