Comparison of the inhibition of commensally and enteropathogenic E. coli strains in the presence of Eucalyptus microcorys leaves extract in aquatic microcosm

This study aimed to assess the inhibition of the commensally and enteropathogenic E. coli strains in aquatic microcosm under various concentrations of Eucalyptus microcorys leaves extract incubated under different temperatures. The extract concentrations were 1%, 1.5% and 2%. The incubation temperatures were 7°C, 23°C, 37° and 44°C. The abundance of the colony forming units (CFU) of each of the cell strains in the presence of Eucalyptus extract, decreased in most cases with respect to the increasing of the concentration of aqueous extract and the incubation temperature. The highest CAIRs were registered at 2% of aqueous extract for both cell strains. The highest CAIRs of the commensally E. coli strains were 4.176.h - 1 ,5.722.h-1 , 5.865.h -1 and 6.319.h -1 registered under the incubation temperature 7°C, 23°C, 37°C and 44°C respectively. For the Enteropathogenic E. coli strains they were 3.547.h -1 , 6.112.h -1 , 8.365.h -1 and 7.027.h -1 under the same incubation temperatures respectively. The cell inhibition percentage varied from one strains to another and with respect to the extract concentration and temperature incubation. With each E. coli strains, the highest cell inhibition percentage was registered under 37°C at 1%, and under 23°C and 37°C at 1.5% of the extract concentration. At the extract concentration 2%, the highest values of the inhibition percentages were noted with most of the incubations temperatures. A significant difference was noted between the inhibition rate of commensally and enteropathogenic strains (P<0.05).