Diversity, Physiochemical and Phylogenetic Analyses of Bacteria Isolated from Various Drinking Water Sources

OBJECTIVE: To evaluate the indigenous bacterial strains of drinking water from the most commercial water types including bottled and filtered water that are currently used in Saudi Arabia. METHODS: Thirty randomly selected commercial brands of bottled water were purchased from Saudi local markets. Moreover, samples from tap water and filtered water were collected in sterilized glass bottles and stored at 4°C. Biochemical analyses including pH, temperature, lactose fermentation test (LAC), indole test (IND), methyl red test (MR), Voges-Proskauer test (VP), urease test (URE), catalase test (CAT), aerobic and anaerobic test (Ae/An) were measured. Molecular identification and comparative sequence analyses were done by full length 16S rRNA gene sequences using gene bank databases and phylogenetic trees were constructed to see the closely related similarity index between bacterial strains. RESULTS: Among 30 water samples tested, 18 were found positive for bacterial growth. Molecular identification of four selected bacterial strains indicated the alarming presence of pathogenic bacteria Bacillus spp. in most common commercial types of drinking water used in Saudi Arabia. CONCLUSION: The lack of awareness about good sanitation, poor personal hygienic practices and failure of safe water management and supply are the important factors for poor drinking water quality in these sources, need to be addressed.