17-11: Effect of CBH2 activity and agitation on the hydrolysis of lignin containing biomass

In past studies, JGC Corporation has reported that enzymatic hydrolysis of pure cellulosic substrates, such as filter paper and pulp, could be significantly improved by placing the reaction under static condition. Hydrolysis of 10% filter paper slurry with 6 mg-protein/g-substrate resulted in hydrolyzate with final glucose concentration of 60 g/L under agitated condition of 120 rpm using rotary shaker and baffled Erlenmeyer flasks. Hydrolyzate with final glucose concentration of 90 g/L was achieved under static condition. This improvement was a result of preservation of CBH2, which was especially vulnerable to sheer stress of agitation (Bioresource Technology 121, 154-60, 2012). In this study, hydrolysis of pretreated biomass containing lignin under static condition was investigated. The results showed that the effect of static condition significantly differed between the types of substrate used. Upon the hydrolysis of 20 w/v% steam-exploded sugarcane leaves at the enzyme loading of 3 mg-protein/g-substrate, the glucose concentration of the hydrolyzate increased from 80 g/L to 110 g/L by putting the reaction under the static condition. However, upon the hydrolysis of 20 w/v% steam-exploded sugarcane bagasse, the glucose concentration of hydrolyzate reached 100 g/L even under the agitated condition, and the glucose concentration reached under the static condition was still 110 g/L. Since the increase in glucose concentration under static condition is caused by CBH2, the effect of CBH2 upon hydrolysis of pretreated biomass containing lignin was investigated further using fractionated enzymes.