The Effects of Temperature and pH on Growth Behavior of Streptococcus iniae

The knowledge of physiology of microorganisms such as bacterial pathogens and their growth behavior under various environmental conditions assist not only the prevention and control of bacterial diseases but also help to recognize the optimum condition for producing of their biological productions e.g vaccines. In this study the effect of temperature and pH was assessed on growth behavior of Streptococcus iniae the causative agent of Streptococcosis in fish. The experiments were runned at temperature 25°C, 30°C , 35°C and pH 5.5 ,7 and 8.5. The obtained linear regression showed that the highest growth rate occurred at 35°C and pH 7 as well as at 30°C and pH 5.5 and 8.5,while the lowest growth rate was obtained at 25°C and pH 5.5. Statisticaly the effect of pH on bacterial growth was more effective than temperature . Significant differences were seen in the growth behaviour of the bacterium at different temperature provided in pH 5.5 (P