Enhancement of Catalytic Performance of [alpha]-dextranase from Chaetomium gracile Through Optimization and Suitable Shear Force

Dextran causes negative impact on the normal production of sugar industry. Traditional removal methods have many disadvantages. 6-alpha-d-glucan-6-glucanohydrolase (EC 3.2.1.11) from Chaetomium gracile without food safety concern could remove dextran, but it has low level of enzyme production. The present study aimed to improve [alpha]-dextranase activity to meet industry demand. Consequently, [alpha]-dextranase activity reached 242.8 U/mL when fermentation condition was 29 °C, pH 6.0 and 220 rpm. Meanwhile, ten glass beads were added to fermentation medium when fermentation time was 12 h, which improved enzyme activity by 135.5% with the highest activity. Purified [alpha]-dextranase exhibited excellent thermal stability and surfactants tolerance. [alpha]-Dextranase from C. gracile could remove dextran by 46.6% in mixed sugarcane juice and 14.1% in clarified sugarcane juice. It had similar dextran removal efficiency with commercial enzymes. These evaluations showed that [alpha]-dextranase had great potential in removing dextran in sugar industry.