Fig. 4

Production of total reducing sugar (a), cellobiose (b) and glucose (c) by C. thermocellum strains under various cellulose-saccharification conditions. Cells of both ∆pyrF (closed symbols) and ∆pyrF::CaBglA (open symbols) were cultivated for 36 h in the cell-cultivation stage. For aerobic treatment (Aerobic), the cultures were transferred into 250-mL sterile flasks shaking at 170 rpm aerobically. For acidic treatment (pH 5.5), the pH value of the broths was adjusted to 5.5 by adding 1 N HCl in an anaerobic chamber. For BGL treatment (red square), 15 U/g cellulose of CaBglA protein was added at the beginning of the saccharification process. Hydrolysis setups carried out under anaerobic condition without pH adjustment were used as the control (Untreated). 100 g/L Avicel was supplemented to initiate the cellulose hydrolysis under various conditions with different treatments. Values are average ± standard deviation based on three independent replicates. *p < 0.01, ∆pyrF::CaBglA vs. ∆pyrF (open vs. closed symbols). #p < 0.01, ∆pyrF::CaBglA vs. ∆pyrF with free CaBglA (open circle vs. red square)