*2.2. Enzyme Preparations*

Three different enzyme preparations (Table 2) were used in this study in different combinations. Dry B1 host preparation represents a complex of cellulases and xylanases obtained by highly productive recombinant *P. verruculosum* strain after UV-mutagenesis [13,14]; dry B1-XylA preparation was obtained by recombinant *P. verruculosum* strain after heterologous expression of *P. canescens* xylanase A [15]; and dry F10 preparation was obtained by recombinant *P. verruculosum* strain after heterologous expression of *Aspergillus niger* β-glucosidase (cellobiase) [16].


**Table 2.** Enzyme preparations.

Activities of enzyme preparations (Table 2) toward carboxymethylcellulose (CMC), barley β-glucan and birch wood xylan were determined by detection of reducing sugars release using Somogyi-Nelson assay [17–19]. Enzyme activities were assayed for 10 min at pH 5 (0.05 M Na-acetate buffer) and 50 ◦C using a substrate concentration of 0.5% in the reaction mixture [20]. CMCase, β-glucanase and xylanase activities were expressed in international units. One unit of activity corresponds to the quantity of enzyme releasing 1 µmol of reducing sugars (in glucose equivalents) per minute.

Enzyme activity toward *p*-nitrophenyl glucopyranoside (pNPG) was determined by detection of *p*-nitrophenyl release by a photometric assay. Enzyme activity was assayed for 10 min at pH 5 (0.05 M Na-acetate buffer) and 40 ◦C using a substrate concentration of 10 mM in the reaction mixture. One β-glucosidase unit of activity is the amount of enzyme which liberates 1 µmol of *p*-nitrophenol per minute [21].
