Objectives: This study was performed in order to detect indicator bacteria in drinking spring water (DSW) samples in Seoul Metropolitan City, and to identify their genus through 16S rRNA sequencing and then assessing the genetic relation of their strains. Methods: For indicator bacteria detection and identification of total coliforms, we analyzed DSW between the spring and summer seasons. In particular, DSW samples were chosen from sites repeatedly found unsatisfactory in recent years. Results: Heterotrophic plate counts of DSW in the spring and summer season were investigated in the range of 0-550 and 0-800 CFU/mL, respectively. Total coliforms of these were 0-1,900 and 0-2,100 CFU/100mL, fecal coliforms were 0-600 and 0-550 CFU/100mL, and Escherichia coli were 0-7 and 0-326 MPN/100mL. The detection ratio of fecal pollution indicators and that of fecal coliforms increased to 58.6% in the summer from 12.5% in the spring and Escherichia coli increased to 51.4% from 4.7%. As a result of genetic analysis on the isolated bacteria, the genus of total coliforms was classified in the order of Enterobacter spp. 12.7%, Serratia spp. 7.3%, E. hermanii 6.4%, Rahnella spp. 5.5%, Hafnia spp. 4.5%, Escherichia coli 3.6%, Klebsiella spp. 3.6% in the spring season. In the summer season, it was classified in order of Klebsiella spp. 16.6%, Enterobacter spp. 13.0%, Escherichia coli 11.0%, Serratia spp. 8.6%, Raoultella spp. 7.0%, Kluyvera spp. 5.6% and Citrobacter spp. 3.0%. Conclusions: The increase of fecal pollution in summer indicates that special attention to drinking DSW is required.
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