Isolation, Identification and Distribution of Gram Negative Bacterial Isolates Contaminating the Drinking Water of Al Gedarif City

Zeinab J. Abdel Daim; Awad M. Abdel-Rahim; Abdulwahab Ali Ahmed

Zeinab J. Abdel Daim Al Gedarif State, Water Corporation Laboratory
Awad M. Abdel-Rahim Center of Biosciences & Biotechnology, Fac. of Engineering &
Abdulwahab Ali Ahmed Faculty of Agriculture, University of Al Gedarif

Abstract

In this study, the possible aerobic Gram-negative bacteria were isolated from the main sources of drinking water in Al Gedarif city (raw and treated waters of Atbara River, main reservoirs and zeer waters of all sources). The isolates were identified using the manual identification tests (primary and biochemical). The primary tests identified the isolates up to the genera level. The results indicated that the isolates belonged to four genera (Neisseria, Aeromonas, Vibrio and Pseudomonas), in addition to Enterobacteria which include Escherichia, Enterobacter, Citrobacter, Klebsiella, Salmonella, Shigella, Erwinia, Providencia, Proteus, Serratia and Yersinia. However, the biochemical tests identified the isolates up to the species level. The bacterium E. coli was the most predominant one among the Gram-negative isolates. Moreover, different species of other genera were also identified. The standardized system (Analytical Profile Index- API 20 E) was used to confirm the identification of the Gram-negative rod species. The study also included the distribution of the identified species in the different sources. It was found that E. coli was found in almost all sources. However, the other bacterial species were detected in some of the sources and absent in the others. On the other hand, many species were not detected in any of the underground sources.In this study, the possible aerobic Gram-negative bacteria were isolated from the main sources of drinking water in Al Gedarif city (raw and treated waters of Atbara River, main reservoirs and zeer waters of all sources). The isolates were identified using the manual identification tests (primary and biochemical). The primary tests identified the isolates up to the genera level. The results indicated that the isolates belonged to four genera (Neisseria, Aeromonas, Vibrio and Pseudomonas), in addition to Enterobacteria which include Escherichia, Enterobacter, Citrobacter, Klebsiella, Salmonella, Shigella, Erwinia, Providencia, Proteus, Serratia and Yersinia. However, the biochemical tests identified the isolates up to the species level. The bacterium E. coli was the most predominant one among the Gram-negative isolates. Moreover, different species of other genera were also identified. The standardized system (Analytical Profile Index- API 20 E) was used to confirm the identification of the Gram-negative rod species. The study also included the distribution of the identified species in the different sources. It was found that E. coli was found in almost all sources. However, the other bacterial species were detected in some of the sources and absent in the others. On the other hand, many species were not detected in any of the underground sources.