Genomic bacterial diversity and quality of bottled drinking water in Lebanon. (c2007)

Abstract

Lebanon is a country on the Mediterranean Sea with a mild Mediterranean climate, and abundance of fresh water falling on its mountains. Several problems face the water sector in Lebanon, with natural and human causes leading to the quantitative and qualitative deterioration of the water reserves. The lack of sewage systems and the lack of control on water quality has led to more and more people to use bottled waters as a source for drinking water. Bottled water companies in Lebanon use mainly springs located in the highest mountains of Lebanon. In this study the hygienic quality of bottled water was studied over a period of one year using tests for indicators of contamination such as coliforms, Aeromonas spp., Pseudomonas spp., Enterococcus spp. and total hetrotrophic bacterial counts. This study was carried out on the major brand names of Lebanese bottled water which are widely consumed in the market. These brands are Brand a, Brand F, Brand D, Brand C, Brand B and Brand E. In this study 30.7% of recovered pseudomanads from tested samples where confirmed as P. aeruginosa, of the 15 isolated colonies on the Aeromonas medium only 4 were confirmed to be Aeromonas sp. (26.7%), faecal coliforms were not detected in any of the tested bottled drinking water samples and no enterococci were isolated fi-om any brand. Brand A, Brand B and Brand F all had a mean HPC (in all four batches) less than 500 cfu/ml, while the number was 677 cfulml in Brand E bottled water. However, Brand C and Brand D had mean HPC counts of 4022 cfu/ml and 4923 cfulml. The identification of organisms using the Biolog and API systems in this study revealed that with 46% of the samples different results were obtained, while 44% were not identified using the Biolog system and only 10% gave a matching ID when compared to the ID obtained by using 16S rDNA sequencing. The 16S rDNA identification resolved the ambiguity observed with the Biolog identification system. The overall microbial quality of Brand A and Brand F were the most acceptable and within all standards. The microbial quality of Brand B and Brand E were also acceptable although Pseudomonas aeruginosa was detected in both brands, while Aeromonas sp. CDC 715-84 was isolated from 75% of the tested Brand C bottles. The HPC count was very high and did not adhere to international or Lebanese standards in 50% of the tested batches of Brand C and in 100% of tested batches in Brand D. The identified microorganisms gave a fingerprint that showed that all tested brands had a fixed source throughout this study except Brand B which had a constantly changing source. Seasonal variation did not have any significant effect on water quality. Moreover, this study showed that results obtained using the Biolog system for the identification of environmental samples should be carefully interpreted. The quality of bottled drinking water in Lebanon should be properly monitored.