Distribution and characteristics of geosmin and 2-MIB-producing actinobacteria in the Han River, Korea

Abstract

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.