Fowl cholera is a contagious bacterial disease of domesticated and wild avian species caused by infection with Pasteurellamultocida. This study was undertaken to investigate the effect of some different parameters as pH and agitation, air with DO (Dissolved oxygen) cascade to increase the production of dry cell mass from the fermentation of Pasteurellamultocida. These different kinetic parameters were carried out in three cultures containing two litters of Brain Heart Infusion broth media in 5 L fermentor (New Brunswick). The first culture (A) conditions were ; at 37 ºC, air flow 0.5 L/min, agitation frequency 90 rpm, dissolved oxygen was 80% and adjustment pH with 1 N NaOH, culture (B) was carried out under the same conditions with no pH adjustment. In addition, culture (C) was carried out with Agitation/Air/DO cascade, the set point of agitation was 90- 200 rpm, air flow 0.5-2 L/min. Culture A gave the highest optical density (OD) compared to culture B and culture C. The values of OD were 2.1, 1.7 and 1.5 respectively. Also, the highest dry cell mass (3.1 g/L), (2.7 g/L) were obtained in culture A and culture B respectively, but the lowest dry cell mass (2.2 g/L) was obtained from culture C with the agitation, air with DO cascade. The present study concluded that it adjusting pH, using low air flow and low agitation gives the highest yield of dry cell mass.
