Effect of Impeller Number and Position on Growth Yield and Virulence of Bordetella pertussis Strain 509 During Large Scale Batch Fermentor Cultivation

Abstract

Studies have been undertaken to investigate, the effect of impeller number and its position upon the growth yield of Bordetella pertussis strain 509 during large scale batch cultivation. It was shown that, the maximum growth yield opacity was found to be 70 IOU mLG at 48 h cultivation in single impeller fixed at the bottom position of fermentor vessel. Whereas the optimal and moderate culture opacity 60 and 50 IOU mLG was observed during the two impellers mounted at two different positions on the shaft. Similarly the least growth yield was obtained during three impeller located at top, middle and bottom region of the shaft and the final opacity was found to be 30 IOU mLG at the end of 48 h cultivation with an increasing of culture pH 8.02. However, in two impeller combination experimental study also showed moderate growth yield at 48 h could give to homogenized mixing and good aeration. Thus, the two different location of the impeller combination influences two vortex flows, enhances optimal growth rate, viz; the lower impeller act as gas disperser and creates radial velocity with higher rates of air dispersion, whereas the upper impeller pumps the broth towards down thus the combined agitation of the broth leads to good mixing and even transfer of Dissolved Oxygen (DO2) to the growing cells and found moderate bacterial growth. In the combination of three impellers mounted at three different positions experimental study shown that, lesser growth yield at the end of 48 h cultivation, due to higher forth accumulation.