Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03

An extracellular endoglucanase was isolated from the culture liquid of xylanase producing strain Aspergillus niger B03. The enzyme was purified to a homogenous form, using consecutive ultrafiltration, anion exchange chromatography, and gel filtration. Endoglucanase was a monomer protein with a molecular weight of 26,900 Da determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 28,800 Da determined by gel filtration. The optimal pH and temperature values for the enzyme action were 3.5 and 65ºC respectively. Endoglucanase was stable at 40ºC, pH 3.0 for 210 min. The substrate specificity of the enzyme was determined with carboxymethyl cellulose, filter paper, and different glycosides. Endoglucanase displayed maximum activity in the case of carboxymethyl cellulose, with a Km value of 21.01 mg/mL. The substrate specificity and the pattern of substrate degradation suggested that the enzyme is an endoglucanase. Endoglucanase showed a synergism with endoxylanase in corn cobs hydrolysis.

Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03.

An extracellular endoglucanase was isolated from the culture liquid of xylanase producing strain Aspergillus niger B03. The enzyme was purified to a homogenous form, using consecutive ultrafiltration, anion exchange chromatography, and gel filtration. Endoglucanase was a monomer protein with a molecular weight of 26,900 Da determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 28,800 Da determined by gel filtration. The optimal pH and temperature values for the enzyme action were 3.5 and 65 °C respectively. Endoglucanase was stable at 40 °C, pH 3.0 for 210 min. The substrate specificity of the enzyme was determined with carboxymethyl cellulose, filter paper, and different glycosides. Endoglucanase displayed maximum activity in the case of carboxymethyl cellulose, with a Km value of 21.01 mg/mL. The substrate specificity and the pattern of substrate degradation suggested that the enzyme is an endoglucanase. Endoglucanase showed a synergism with endoxylanase in corn cobs hydrolysis.

Optimization of nutrient medium containing agricultural wastes for xylanase production by Aspergillus niger B03 using optimal composite experimental design.

The xylanase biosynthesis is induced by its substrate - xylan. The high xylan content in some of the wastes like corn cobs and wheat bran makes them an accessible and cheap source of inducers. Nutrient medium for xylanase biosynthesis in submerged cultivation of Aspergillus niger B03 has been optimized. The optimization process was analyzed using optimal composite experimental design and response surface methodology. The predicted by the regression model optimum components of nutrient medium are as follows (g/l): (NH(4))(2)HPO(4) 2.6, urea 0.9, corn cobs 24.0, wheat bran 14.6 and malt sprout 6.0. Five parallel experiments have been carried out, at definite, optimum components concentrations of the nutrient medium, and a mean value of the activity Y=996.30 U/ml has been obtained. The xylanase activity, obtained with the optimized nutrient medium is 33% higher than the activity, achieved with the basic medium.