Actinobacteria can be one of the causes of earthy and musty odors in drinking water. In this study, the distribution and odor producing ability of actinobacteria isolated in the Han River as a source of tap water were investigated. Actinobacteria were detected in low concentration from December to February and this gradually increased in March and April. The number of actinobacteria detected was particularly high in April (63 CFU/mL), July (45 CFU/mL), and October (39 CFU/mL) due to the influence of rainfall. Actinobacteria with geosmin-producing genes were detected mainly in March and July. In contrast, actinobacteria with 2-MIB-producing genes were detected mainly in October. There was a difference in the time when actinobacteria with the geosmin and 2-MIB-producing gene were highly detected in the river. Also, the types of actinobacteria with the geosmin and 2-MIB-producing gene were different. More than 70% of the geosmin inducer gene was isolated in Streptomyces, but the 2-MIB inducer gene was detected in various genera of actinobacteria as well as Streptomyces. The detection of odorous substances in March and October when cyanobacteria were not detected, or the detected number was low, suggested that actinobacteria could be a cause of odor inducers in the Han River.
DNA extraction methods were evaluated to reduce PCR inhibitors and quantify Helicobacter pylori directly from water samples using real-time PCR. Three nucleic acid extraction methods were evaluated for different types of water samples. While the QIAamp DNA mini kit for tissue was suitable for DNA extraction from treated water, the QIAamp DNA stool mini kit was still efficient in analyzing samples from river water after heavy rain and with high concentration of PCR inhibitors. The FastDNA SPIN Kit for Soil could extract DNA effectively from microbes in river and stream waters without heavy rain. Immunomagnetic separation (IMS) was used prior to DNA extraction and was a useful tool for reducing PCR inhibitors in influent and stream samples. H. pylori in various waters could be quantified directly by real-time PCR while minimizing the effect of PCR inhibitors by an appropriate method through the evaluation of DNA extraction methods considering the characteristics of the matrix water. The findings of the present study suggest that the types or characteristics of water sample by source and precipitation are an important factor in detecting H. pylori and they can be applied when detecting and monitoring of other pathogens in water.
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