Ultrasound assisted production of a fibrinolytic enzyme in a bioreactor

The present work illustrates ultrasound assisted production of a fibrinolytic enzyme at 1 L bioreactor scale from Bacillus sphaericus MTCC 3672. To alleviate the shortcomings of one factor at a time method of optimization, central composite rotatable design of response surface methodology was employed for optimization of ultrasound assisted production. Different process parameters such as irradiation time, duty cycle and power of ultrasound were varied in 3 different levels in 11 experimental runs. For evaluating mass transfer enhancement effect of ultrasonication on production, control non sonicated fermentation was optimized by varying different agitation speed (300–500 rpm) and aeration rate (8.33–33.33 cc/s). Optimized ultrasonication protocol resulted in 1.48-fold increase in fibrinolytic enzyme yield as compared to non sonicated fermentation, which comprised of ultrasound irradiation at 25 kHz for 10 min with 40% duty cycle and 160 W power on 12 h of growth phase in 1 L bioreactor operated at 400 rpm agitation speed and 16.66 cc/s aeration rate. Declined glucose concentration from 0.1% w/v (non sonicated control run) to 0.05% w/v and breakage of cells cluster emphasized on increased substrate utilization potential and enhanced convection of ultrasound assisted fermentation in a bioreactor. Deliverables of current studies will provide significant insights for enhancement of productivity of various enzymes at a bioreactor level.