الفهرس 
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Abstract
The isolated bacterial strains (E. coli) were isolated from raw water samples that were collected from a branch of Nile River in El-Sharkia governorate (Egypt). Moreover, five sewage water samples were used for isolation of phages (ECP1, ECP2 and ECP3) that was active against isolated E. coli strains. These phages were found only in sewage water samples that were collected from sewage plant of abukhalil, sewage plant of awja and a branch of bahr elbakar canal. Antibiotic resistance in E. coli W1 and E. coli W2 that were infected by isolated phages were examined to differentiate between them by measuring resistance to twelve antibiotic drugs. According to plaque morphology and electron microscopic studies, phages were distinguished into three phages, which were belonging to the Myoviridae family .Increasing in the host age lead to inhibition of the phage infectivity. Using 7 isolates of Escherichia coli in addition to 7 various bacterial species clarified that phage ECP1 was highly specific to infect E. coli W1, on the other hand, phages ECP2 and ECP3 were highly specific to infect E. coli W2. The three phages exhibited different rates of adsorption and burst sizes but they had the same latent period (30 min) and rise period (30 min) The three isolated phages were very sensitive to heat inactivation; no survivors could be recorded after 10 min of exposure time to 60 0C. Also, the profile of three isolated phages inactivation after different times intervals exposed to UV-irradiation at different heights of 15 and 30 cm from the irradiation source was examined. Increased UV-irradiation doses decreased the plaque numbers of the three isolated phages.