Technology optimization and kinetic characteristics of β-glucosidase production by fermentation of Aspergillus niger M85 with wheat bran

The fermentation technologies for β-glucosidase production by Aspergillus niger M85 with wheat bran as the only carbon source was optimized through single-factor test and orthogonal test and the kinetics models of fermentation under optimized technology were investigated. When wheat bran of 2% was added into medium, the optimum technologies for Aspergillus niger M85 fermentation in shake flasks were rotational rate of (200±5)r/min and temperature of (30±0.5)℃ with inoculum amount of 15% while in 5 L fermentors were (400±10)r/min and (30±0.5)℃ with inoculum amount of 10%. Time course analysis of fermentation showed that the changes in the kinetic curves in shake flask and 5 L fermentor possessed a similar tendency. After 3 days under the optimum technologies, β-glucosidase activity of fermentation reached 1103.73 U/mL and 1318.82 U/mL in shake flasks and 5 L fermentor, respectively, where the conversions of wheat bran to β-glucosidase were 55186.61 U/g and 76085.82 U/g, respectively. Based on Monod equation and Luedeking-Piret equation, the kinetic models describing cell growth and β-glucosidase production were established. The results would provide a technical basis for the factory production of β-glucosidase from wheat bran.