Comparing the ability of C
p-nitrophenyl-β-d-glucopyranoside (p-NPG) was purchased from Sigma–Aldrich (Switzerland). H2SO4 was purchased from Burdick and Jackson. NaOH was purchased from Loba Chemie. DNS reagent was prepared by mixing 10.6 g of 3,5-dinitrosali-cylic U-50488 and 19.8 NaOH into 1416 mL of distilled water in a stirred beaker. Rochelle salts (potassium sodium tartrate) (306 g), phenol (8.1 g) and sodium sulphite (8.3 g) were then added ( Al-Zuhair, 2008).
2.3. Preparation of macroalgae mixture
U. rigida were ground with a laboratory blender (Product Division USA, Torrington, CT). Different concentrations were prepared from 10% to 80% (W/V) in water.
2.4. A. niger enzymes production
2.5. β-Glucosidase and CMCase activities assays
The β-glucosidase activity was determined using 1 mM pnitrophenyl-β-d-glucoside (pNPG) as substrate (in 100 mM citrate buffer pH 5). An aliquot of 0.2 mL of 1 mM pNPG was incubated, with an appropriate diluted enzymatic preparation, at 50 °C for 15 min. The reaction was stopped by adding 0.5 mL Na2Co3 1 M; the liberated p-nitrophenol (pNP) was measured at 400 nm ( Brini et al., 2010).