The specificity of the xylanases was verified by assaying the
activity against different substrates. Xylanase activity was measured
on birchwood and oat spelts xylans. Endoglucanase (CMCase) and
exoglucanase (Avicelase) activities were assayed in a reaction mixture
with carboxymethylcellulose (CMC) and microcrystalline cellulose
(Avicel), respectively. Substrates at 1% (w/v) were prepared in 0.05 M
sodium acetate buffer pH 5.5 and appropriately diluted enzyme
solution. Reducing sugars were quantified with the DNS acid reagent
and the absorbance was measured at 540 nm. One unit of activity was
defined as the amount of enzyme required to release 1 μmol of
product equivalent per min in the assay conditions at 50°C.