بررسي اثر استرس هاي محيطي بر روي ويژگي هاي فنوتيپيك و خواص بيوشيميايي Pseudomonas aeroginosa ATCC 27853

Survey of a variety of environmental stress conditions on phenotypic and biochemical characteristics of Pseudomonas aeroginosa ATCC 27853

In this study a variety of environmental stresses such as temperature, different concentrations of sugars, sodium chloride, ethanol and heavy metals were studied on Pseudomonas aeruginosa ATCC 27853. Following exposure to different stress conditions for 20 minutes, growth patterns were studied on Blood Agar Medium. Also, viability of the bacterium on basal and differential media were studied. Microscopical studies showed significant changes on morphological and biochemical patterns. P. aeruginosa ATCC 27853 survived at temperature of 85 ° C. Maximum tolerance in acidic and basic pH were in values 3 and 12, respectively. This bacterium was resistant to ethanol concentration up to 55%. Maximum tolerance for selected heavy metals were 0.7% CoCl2, 0.7% HgCl2 .It was able to survive at sucrose concentration up to 35%. The increasingly high level of resistance of the Pseudomonas aeruginosa to stressful conditions is the main reason for the high prevalence of this bacterium in hospital settings and it is contribution to nosocomial infections.