10-20: Enzymatic conversion of cellulosic substrates in the process of surface active additives, laccase and protease inhibitors

Enzyme stability is of great significance for practical processes of cellulose saccharification and biofuel production.  Surfactants have been suggested to increase enzymatic digestibility of cellulose.  The main mechanism behind their action is believed to be related to preventing unspecific adsorption of enzyme on the lignin that is closely associated with the cellulose and hemicellulose in the plant cell wall structure.  BSA has been suggested to reduce adsorption of cellulases and β-glucosidase on lignin, improving cellulose degradability.  Contradictory results for cellulose degradability in the literature have been reported for treatment of pretreated cellulosic material incubated with laccases prior to cellulose hydrolysis.  Proteases that can also contribute to inactivation effect of enzyme preparations used for cellulose saccharification may be present in the preparations themselves.  The combined effects are complex and hence were studied in a systematic experimental design that varied types and concentrations of surface active additives, laccases, and protease inhibitors in the enzyme hydrolysis of liquid hot water pretreated cellulosic material.  Improvement in cellulose conversion (more than 10%) after 48h was observed for enzyme hydrolysis of liquid hot water pretreated corn stover treated with laccase, PEG 4000 and non-ionic surfactants (Tween 20 and 80).  While PEG 4000 and non-ionic surfactants may stabilize the enzymes, the effect of laccase is small and depends on lignocellulosic substrate.