الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
The year was divided into four seasons for collecting water samples, which are fall (November 2020), winter, spring and summer 2021. Samples were collected from the Nile River, specifically the entrance to the drinking water company in Mansoura, before treatment and after a sample of the water leaving the treatment plant ( outlet), and a water sample from the bacteria lab at the Faculty of Science, Mansoura University, and a water sample from a house in Mansoura (the study residence). In addition to collecting four types of bottled drinking water that are sold in the Egyptian markets (Hayat, Dasani, Aquafina, Nestle). After that, the bacterial isolates present in these samples were isolated and purified, and the result was to obtain 15 isolates from November sample and 10 isolates from the March samples. While for July, which represents the summer season, the largest number of isolates was 27. This is due to the high temperature is suitable for the growth of most microorganisms, and December isolates were 10. Most of the isolates were obtained from untreated Nile water and some very few isolates from treated water (outlet) from Mansoura Treatment Plant in Dakahlia and home water. The presence of these bacteria may be attributed to human error during experiments or during sample collection. A coliform bacteria test was conducted for all collected samples, and the result was negative for all water samples after treatment, bacteria laboratory water samples, and also the home water sample, and the result of the coliform test for bottled drinking water was all negative. But the result of the coliform test for untreated drinking water in the four seasons in which the samples were collected, the result was positive in the presumptive test, and there was a change in color in the McConkey broth medium, as well as gas formation before 24 hours from injecting the water samples into the broth medium. But in the confirmatory test, which is the cultivation of isolates on a selective nutrient medium (EMB) some isolate growth was metallic green as in the first sample (N1, N2, N3, N5, N6, N10) and in the second sample (MB1 and MB2), in the third sample (jB9, jB10, jB12, jB13, jB14 jB15, jB18, jB20). In the complete test, which is the cultivation of the bacterial isolates which appeared in metallic green in the confirmatory test on a medium containing lactose sugar, gas appeared and a change in color in some bacterial isolates, such as the first sample (N2, N5, and N10) and the second sample (MB1 and MB2) and in the third sample (jB9, jB10, jB12, jB13, jB14 jB15, jB18, jB20).