Evaluation and comparison of the effect of ORS and pH stress on the biofilm formation and planktonic condition of E.coli O157: H7

Aims and E. coli O157: H7 is a bacterium from the family Enterobacteriaceae which are Gram negative cocobacilli، causing gastrointestinal diseases such as Diarrhea، Hemorrhagic colitis and hemolytic uremia. The aim of this study was to examine E. coli O157: H7 in plankton and biofilm status under stressed conditions of pH and ORS powder at 37 0C and then comparing their shape both in microscopic (bacterial shape) and macroscopic levels (bacterial colonies). Bacterial strains of E. coli O157: H7 were purchased from Razi Vaccine and Serum Manufacturing Co. with No. (RITCC) 2323. The bacteria were placed in liquid Nutrient Broth culture media and then transferred to Nutrient Agar culture media into plates to examine colonial shape. Next، colonial and bacterial shapes were examined by gram dying. Counting the number of live bacteria under stressed conditions was done by poor plate method and diluting preparation. In order to determine the power of biofilm formation under stressed، microtitration plate was used and read by Elisa Reader. Bacterial shape is affected by stressed conditions. Under stressed conditions، colonial morphology and bacterial shape significantly change and the shape tends to transform to Cocci and bacilli in order to survive longer. Survival of bacteria under stressed conditions is more in biofilm state than Plankton. these changes have a direct relationship with the survival of most bacteria in the digestive tract preventing the natural effect of gut antibacterial compounds on bacteria and the resistance of bacteria in biofilm is more than plankton.