Investigating the Severity of Environmental Stress Conditions on Growth, the Protein Profile and Biochemical Characteristics of Pseudomonas aeruginosa ATCC 27853

Pseudomonas aeruginosa is the main cause of nosocomial infections, and is resistant to most antibiotics, this study aimed to evaluate the effects of different stress conditions on growth, the protein profile, and biochemical characteristics of this bacterium. The cells of P. aeruginosa ATCC 27853 in the logarithmic phase were exposed to different stress factors such as sucrose concentration, ethanol, acid, osmotic pressure, and CoCl2. Following each stress condition, the growth and the survival of bacterial cells were determined. Microscopic observation showed morphological changes in different stress conditions. P. aeruginosa ATCC 27853 tolerated up to pH 3, 55% (V/V) ethanol, and CoCl2 up to 7% (W/V), and beyond these amounts, the bacterium lost its ability to survive. Maximum tolerance to sucrose was about 35% (W/V). The results showed that different stress conditions could not effect on the main biochemical characteristics of P. aeruginosa ATCC 27853. Scanning electron microscopy of the cells exposed to different stress conditions showed wide changes in the morphology of cells. In addition, upon treating to different stresses significant changes were observed in the protein profile of P. aeruginosa ATCC 27853 according to SDS-PAGE analysis. It can be concluded that severe environmental stresses have great effects on the growth pattern, phenotypic characteristics, and protein profile of P. aeruginosa ATCC 27853. If the stresses induced all at once, they will cause the death, but if they are affected slowly and for longer period, most bacteria will be able to repair the damaged parts, and the growth of will resume.