Comparison of PCR Technique with MPN Method in Identification of Coliform Bacteria in Water

Microbial pathogens are among factors posing significant threats to hygiene issues for water and wastewater. Thus indicator bacteria are used for detection of relative risk of fecal contamination and potential presence of pathogens in water. However, indicator organisms bear some disadvantages decreasing their effectiveness as ideal indicators of microbial pathogens in water. In addition, conventional methods for detection of these pathogenic viruses, bacteria, protozoa and worms tend to be inaccurate, time consuming and expensive. Polymerase Chain Reaction (PCR) technique has been recommended as a diagnostic technique which has been tested and brought about impressive results. In this paper, following designing primer related to genomic segment of Lac Z it is duplicated using PCR technique in order to isolate bacteria from samples of drinking water. This genomic segment encodes β-galactosidase enzyme in Colifrom bacteria. Then results are compared with multiple-tube fermentation technique by MPN method. Sampling was performed in 18 wells of drinking water in Qom’s villages and samples were tested using PCR and MPN techniques. Of the total samples tested, 3 samples responded positively to MPN technique and 8 samples responded positively to PCR technique. Findings suggest higher accuracy in PCR compared to MPN.