Abstract

As the pure drinking water is inevitable for good health, it is necessary to evaluate it for bacterial contamination. This study was conducted on the different drinking water sources of Kohat, a Northern-Western District of Pakistan. Sampling was done from different drinking water sources including tap water, tube well water, home-well, bore-well and springs. Physiochemical analyses including pH, temperature, turbidity, total dissolved solids and electrical conductivity showed that all water samples were within ranges of the values prescribed by the World Health Organization. A total of 79 bacteria isolated from different samples were characterized. Eighty two percent of the strains were Gram negative and 64% of the total Gram positive bacteria were spore forming. The physiological characterization showed that 30.4% of the total bacterial strains were obligate aerobes while the rest were facultative anaerobes. Biochemical characterization and identification depicted enormous bacterial diversity where sixteen genera could be tentatively identified. Identification of 24 of the strains was further validated by using API 20E kit. Furthermore, the selected strains were analyzed for pH, temperature optimization and NaCl tolerance. Pseudomonas sp were the most abundant bacteria followed byBacillus sp. Some of the coliform bacteria could also be identified which present a potential health hazard.

Key words: API 20E, bacterial diversity, water-borne pathogens.