Abstract
Heterotrophic bacteria isolated from finished and tap water samples were examined for hemolysis activity to determine their virulence factors. Eleven colonies expressing hemolysis activity were identified by partial 16S rDNA sequencing and phenotypic test using BiologTM. All eleven strains were identified at the genus level and eight strains were identified at the species level by 16S rDNA sequencing. On the other hand, phenotypic test could identify only two strains at the genus level and four strains at the species level. Furthermore, three of four strains identified at the species level by phenotypic test might have been misidentified. Therefore, it was suggested that phenotypic test is inadequate identifying heterotrophic bacteria in drinking water, whereas 16S rDNA sequencing is a useful identification tool for them. The eleven strains identified have been reported to be food poisoning bacteria or opportunistic pathogens. Since these opportunistic pathogens exist in heterotrophic bacteria, both appropriate water quality control and further study should be continued for safe tap water supply.
