Figure 6

The effect of polyols on thermostability of the purified xylanase from A. pullulans CBS 135684 cultivated in basal medium containing 1% corncob. (a) The enzyme solutions were preincubated at 70°C without the presence of substrate for various times in the presence of glycerol (Δ), sorbitol (▲), mannitol (■), xylitol (□) and ethylene glycol (EG; ο) at a concentration of 0.5 M prior to enzyme assay at the optimal condition. (b) The enzyme solutions were incubated under the same condition as in (a) with the presence of sorbitol at concentrations of 0.25 M (♦), 0.50 M (■), 0.75 M (ο) and 1.00 M (▲) prior to enzyme assay at the optimal conditions. The residual xylanase activity was calculated as the percentage of initial enzyme activity (before incubation). Experiments were performed in triplicate (N = 3) and error bars indicated standard deviation.