"The Effect of Some Physical Parameters on The Growth Rate of E. Coli and K. Pneumoniae"

Abstract

This study aims to investigate the influence of some environmental factors including temperature, pH, and pressure on the growth rates of Escherichia coli and Klebsiella pneumonia due to its importance for developing effective prevention and treatment strategies. E. coli and K. pneumonia are common pathogens in humans and important members of the family Enterobacteriaceae, that are involved in many infections. In this study, growth rates were measured at different temperatures ranging between 25°C, 30°C, 37°C, and 42°C, over incubation periods of 24, 48, and 72 hours. Growth rates were also assessed at five pH levels: 4, 5, 7, 9, and 10. Moreover, we investigated the effect of five different pressure conditions on bacterial growth rates including 1 atm (standard atmospheric pressure), 5 atm, 10 atm, 20 atm, and 30 atm using liquid nutrient broth cultures and the usual nutrient agar plate count technique.Our results demonstrated temperature-dependent variations in bacterial growth. As, it showed distinct growth patterns for each bacterium, with optimal growth observed at 37°C. Conversely, higher temperature (42°C) was accompanied by metabolic stress and reduced viability over prolonged incubation periods reaching 72 hours. However, E. coli showed better tolerance for higher temperatures compared to K. pneumoniae, which suggested that E. coli might have a higher adaptability to temperature fluctuations and explained its prevalence in a broader range of environments.Moreover, both E. coli and K. pneumonia exhibit optimal growth at a neutral pH of 7, with