Countercurrent saccharification

At pH 4.8 and 50°C, semi-continuous countercurrent saccharification was performed using α-cellulose substrate and Novozymes CTec2 cellulase. Every second day, solids and liquids were transferred countercurrently and liquid samples were taken to determine sugar concentration in each stage. Train 1 (5 mg protein/g biomass, 8 stages) achieved 87.8% glucose conversion and 102 g/L total sugar. Train 2 (2 mg/g, 8 stages) achieved 56.1% glucose conversion and 65 g/L total sugar. Train 3 (2 mg/g, 16 bottles) achieved 73.6% glucose conversion and 67 g/L total sugar. Compared to 5-day batch saccharification, to achieve the same glucose conversion, enzyme requirements were reduced by factors of 16.8, 8, and 20.5 for Trains 1, 2, and 3, respectively.  These results are very encouraging, so on-going experiments are being performed with industrially relevant feedstocks (corn stover pretreated with lime and lime + shock) and Novozymes CTec3 cellulase + HTec3 hemicellulase.