Abstract
A rapid and quantitative polymerase chain reaction (PCR) method for determining the numbers of two fecal pollution indicators, E. coli and Enterococcus was developed. The quantitative detection of E. coli and Enterococcus was performed on the basis of the uidA and 23S-rRNA gene sequences, respectively. A linear relationship was observed between the log concentration of each gene and the threshold cycle value obtained from the PCR amplification curve. Using these standard PCR curves, the concentrations of E. coli and Enterococcus were measured in environmental water samples collected from a wastewater treatment plant and four bodies of water located in the northern part of Japan. Measurements by the real-time PCR method were compared with E. coli and Enterococcus counts determined by cultivation methods such as membrane filter and MPN analyses. The PCR method gave quicker results and higher E. coli and Enterococcus counts than the traditional cultivation methods. These higher counts suggested the ability of the PCR method to detect DNA from both culturable and nonculturable or dead bacteria. Regression analysis of these measurements showed significant positive correlations between the PCR method and the traditional cultivation methods with correlation coefficients of over 0.7.
