Determining Contamination by Escherichia coli in Water Resources through yaiO Gene Molecular Analysis, Iran
Author(s): Samaneh Ahmadi, Fatemeh Keshavarzi
Recent studies have shown that Escherichia coli (E. coli) are the best indicator for evaluating fecal contamination and possible presence of enter pathogens. The method used at present in Iranian water laboratories for detection of these bacteria (the most probable number or the MPN) method. However, the use of the enzymatic method has expanded to overcome the limitations of the MPN method including its being very time-consuming (it requires 24-96 hours).Fifty drinking water samples were taken from drinking water resources in the rural areas of Kamyaran, the bacteria in the samples were isolated using the MPN test, and initial identification of the purified bacteria was carried out by employing a series of biochemical tests. The Oligo software was employed to determine the sequence characteristics of the designed primers, and the accuracy of the software was confirmed by using the BLAST software. Finally, the stages of genomic purification were carried out by employing the CTAB-NaCl method on the bacterial precipitation.Of the 50 samples taken from drinking ware resources of the rural areas in Kamyaran, 12 were positive in MPN tests. Moreover, use of the MPN test indicated that six of these 12 samples were infected with Escherichia coli. Presence of E. coliin all of the contaminated samples was confirmed using the PCR method and employing the yaiO gene-specific primers. Results showed that although the PCR method is a fast, reliable, and suitable method for detecting bacteria in drinking water, yet it is not possible to use it in the rural areas of Kamyaran at present due to shortages of facilities, laboratory materials and equipment, and specialist staff.