Study On β-glucanase From Bacillus Amyloliquefaciens

It was very important for the beer brewing by using theβ-glucanase in the mashing. Theβ-glucan could be degraded byβ-glucanase specially, the viscosity and turbidity of wort could be decreased, the velocity of wort filtration could be increased and the quality and yield of wort could be improved by using theβ-glucanase. The medium of shaking flask fermentation and fermentation condition of fermentor of producingβ-glucanase was optimized by the Bacillus amyloliquofaciens 5582 which was stored in the lab in this thesis. The preparation processing of solid and liquid enzyme and its application was studied primarily. The main results were as follows:The medium of shaking flasks fermentation of Bacillus amyloliquofaciens 5582 was conducted. The optimal medium compositions (g/L) were determined as: barley flour 40, corn flour 30, bean flour 30, Na2HPO4?12H2O 6, (NH4)2SO4 4, MgSO4?7H2O 1, CaCl2 0.8. It was fermented on 37℃for 60 h, theβ-glucanase activity was 128.55 u/mL, which was increased by 26.08 % compared with the original medium.In 5 L automated jar fermentor, the optimal fermentation condition was: the seed was pitched with 6.67% after culturing 18 h. The fermentation temperature was on 37℃then was cooled to 32℃after 27 h. Air volume was 1 L/ (L·min) and was agitation speed was 500 r/min, theβ-glucanase activity was 182.2 u/mL. It was increased by 28 % compared with the constant temperature fermentation. The pH was about 7.2 in fermentation peak.The pilot scale experiment was investigated in the 8000 L fermentor. The cell number was increased quickly in 24 h, while theβ-glucanase activity was increased slowly and pH was decreased. Theβ-glucanase activity was increased from 24-40 h, and then was reached 249.6 u/mL after 46 h. The cell was autolyzed at that time.1 % diatomite, 2 % CaCl2 and 2 % Na2HPO4·12H2O was added to the fermentation liquid. 4 % adjunct and (NH4)2SO4 with 60% saturation was added to the bright enzyme liquid after agitation and filtration. Finally the solid enzyme was gotten after drying on 55℃. Theβ-glucanase activity in the solution was protected well with the complex stabilizer containing 120 g/L glycerin and 5 g/L xanthan gum and 1 g/L sodium benzoate. The relativelyβ-glucanase activity was 89.5 % stored on room temperature for 120 days. It was increased by 19.5 % comparing with the control.Theβ-glucan content and viscosity of wort was decreased obviously by addingβ-glucanase in the mashing with 1 u/g malt. The application result was similar with the foreign product.