Production of Pectinase Enzymes by Bacillus pumilus in Bioreactor and Investigation of the Effect of Mixing and Airflow Rate

Abstract

Pectinases are a general name for a family of enzymes that catalyze the hydrolysis of glycosidic bonds in pectic polymers. In this study, the effects of stirring speed and airflow rate on the production of endo-pectinase, exo-pectinase and pectin lyase from pectinase group enzymes in a batch bioreactor were investigated. In addition, the oxygen consumption rate and the change of the liquid phase volumetric mass transfer coefficient and the power number for stirring were also calculated. It was determined that the optimum stirring speed for the production of pectinase group enzymes of Bacillus pumilus bacteria was 300 rpm. In experiments where the effect of airflow rate on enzyme activity was investigated, the highest enzyme activity values were obtained at 0.1 vvm. The highest pectin lyase, exo-pectinase and endo-pectinase activities were recorded as 19.5 at the 66th hour, 10.69 at the 28th hour and 102.13 U mL-1 at the 66th hour, respectively at a stirring speed of 300 rpm and an airflow rate of 0.1 vvm. The liquid phase volumetric oxygen transfer coefficient value increased with increasing stirring speed. The highest kLa value was recorded as 0.1524 h-1 at the 26th hour at 300 rpm stirring speed and 0.2623 h-1 at the 60th hour at 400 rpm. The oxygen consumption rate increased in the exponential growing zone and decreased after the exponential growing zone. When the stirring speed was increased, the oxygen consumption rate decreased. At optimum 300 rpm, the power value in the case of aeration to the system was found to be 1.95 W.