Fig. 4.

Effects of exogenous H₂O₂ addition on cellulase performance under ambient air and limited O₂ conditions. CTec3 was incubated with pretreated wheat straw in the presence of 0 (blue circles), 0.01 (red triangles), 0.1 (green squares) and 1 (black diamonds) mg H₂O₂/g slurry added four times (as indicated by the arrows) after the cellulosic material was liquefied. Effects of H₂O₂ were tested under ambient air (panel a) and after purging with N₂ (panel b). For this experiment lids for the reaction tubes with a septum were used and the indicated amount of H₂O₂ was added to the reaction mixture using Hamilton syringes. The first addition was made after about 18 h of incubation at which time the reaction mixtures were liquefied. H₂O₂ was added four times at intervals of about 3.5 h during which the tubes continued incubation at 50 °C