β-Glucosidase assay

β-Glucosidase activity was assayed by incubating the reaction mixture containing 10 mM p-nitrophenyl-β-d-glucopyranoside (pNPG) and purified β-glucosidase in 1:1 ratio for 1 h at 60 °C. The reaction was stopped by adding 2 ml of 1 M Na₂CO₃. The p-nitrophenol release was monitored at λ_405nm in UV–visible spectrophotometer (Jäger et al. 2001). One unit (U) of β-glucosidase was defined as the amount of the enzyme to produce one μmol p-nitrophenol per min under the standard assay conditions and the specific activity was defined as the number of units of β-glucosidase per mg of protein. Total protein content was determined by Bradford method (Bradford 1976).