Evaluation of bacterial diversity in traditional drinking water reservoirs of rural areas: a molecular approach

In Morocco, storage reservoirs are particular systems of water supply in rural areas. These reservoirs are fed by rainwater and/or directly from the river through opened channels, and are used without any treatment as a drinking water by the surrounding population. This study was conducted to evaluate the bacterial contamination of drinking water reservoirs in this rural area, using a molecular approach studying the 16S-rDNA bacterial diversity in water, via Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technique. The application of PCR-DGGE techniques on stored water in the reservoirs showed a high bacterial diversity, including pathogens, namely Salmonella sp., E.coli, Sphingomonas spp. and Aeromonas sp., which indicated a high risk of infection for the user population. Comparative cluster analyses of the DNA based fingerprints revealed the six studied reservoirs according a gradient accumulation of bacterial contaminants from upstream to downstream. The molecular approach in this study gives a very helpful tool to confirm without any doubt the bacterial contamination of drinking water.