Fig. 6

Effect of various constant H₂O₂ feeding rates on the saccharification of steam-exploded birch with Cellic^® CTec2. a The production of Glc4gemGlc and b the glucan conversion. All reactions were carried out with 10% (w/w) DM of birch, 2 mg/g DM of Cellic^® CTec2 in the absence of AscA, in 50 mM sodium acetate buffer at pH 5.0 and 50 °C with constant supply of H₂O₂ (600 µL h⁻¹) using H₂O₂ stock solutions with appropriate concentrations (Table 1). To ensure anaerobic conditions, all reactions were carried out with constant sparging of nitrogen at a flow rate of 100 mL min⁻¹, with the exception of the aerobic control reaction (O₂), which was sparged with air at the same flow rate. “N₂” and “N₂ Cys” stand for the anaerobic control reactions; the latter was carried out in the presence of 0.025% (w/v) l-cysteine hydrochloride monohydrate. All control reactions were run without addition of H₂O₂. Since the glucan fraction of this substrate was only 43.9%, here, in contrast to all other reactions reported in this study, Cellic^® CTec2 was dosed at 2 mg (rather than 4 mg) protein/g DM. Error bars for glucan conversion represent standard deviations of two technical replicates