Figure 6

Schematic of consecutive biological saccharification method based on recycling the hydrolyzed residue. C. thermocellum supplementation with CBM-CglT was only carried out in the first biological saccharification round, without further culturing or addition of any enzymes. To recover free cellulosomes, CBM-CglT, and C. thermocellum cells, fresh pretreated cellulose substrates were added to the hydrolysis slurry and then reabsorbed from the supernatant. A second round of biological saccharification was performed using enzymes recovered by allowing them to bind to fresh substrate and the hydrolysis residue containing C. thermocellum cells. Consecutive biological saccharification using these recycling procedures may be repeated several times. When recombinant C. thermocellum strains overexpressing CglT or CBM-CglT are used in consecutive biological saccharification, addition of thermostable β-glucosidases may not be required. The left and center images are the relative initial biomass containing 120 g/L alkaline-pretreated rice straw and the culturing slurry. The right image shows the appearance of attached cells and CBM-CglT during recycling. ARS, alkaline-pretreated rice straw.