*2.1. Cultivation of Bacteria*

*Escherichia coli* CIP 53126 was obtained from Institut Pasteur Collection, Paris, France. The strain was preserved at í80 °C in Eugon medium supplemented with 10% glycerol. Before each experiment, bacterial cells were pre-cultured on a nutrient agar slant. They were then transferred to a trypticase soy agar and incubated at a temperature of 36 °C ± 1 °C for 16 to 24 h. In addition, one plastic loop of bacteria was transferred to a fresh trypticase soy agar and incubated at a temperature of 36 °C ± 1 °C for 16 to 20 h prior to the test. For testing, one plastic loop of bacteria was dispersed evenly in a small amount of 1/500 nutrient broth (NB) [48] or of sterile distilled water, depending on the test, and the bacterial cell content of the suspension for inoculation was adjusted to about 108 cells/mL with a spectrophotometer (640 nm). The cell suspension was then 10-fold steps diluted, and 1 mL of each dilution was incorporated in trypticase soy agar to determine the number of CFU/mL. The test suspensions were prepared by 10-fold dilutions.
