Outbreaks of 2‐methylisoborneol (2‐MIB) contamination in drinking water sources cause inconvenient odor issues in the water distribution system. In this study, microscopy‐based isolation with physiological and molecular phylogenetic characterization were performed to investigate and characterize the 2‐MIB odor producers that caused an odor problem in the freshwater system of the North Han River in the autumn of 2018. A benthic cyanobacterium was isolated from 2‐MIB odor-issue freshwater samples and was found to be phylogenetically affiliated with Pseudanabaena yagii (99.66% sequence similarity), which was recorded in South Korea for the first time. The 2‐MIB synthesis gene sequences from the odor‐issue freshwater samples showed 100% similarity with those in the P. yagii strains. Protein sequences of 2‐MIB synthase observed in the genome of the isolated strain showed structural and functional characteristics similar to those observed in other Pseudana-baena species. The 2‐MIB production rate increased slowly during mat formation on the vessel wall; however, it rapidly increased after the temperature dropped. The 2‐MIB gene was continuously expressed regardless of the temperature changes. These results suggest that the 2‐MIB odor issue in the North Han River might be caused by the release of 2‐MIB from the mat‐forming P. yagii species in a low‐temperature freshwater environment.
Bibliographical noteFunding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020R1A6A1A03045059) and was conducted as part of the National Treasury Assistance Program of the National Institute of Environmental Research, South Korea.
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
- 16S‐23S rRNA ITS
- 2‐MIB odor
- North Han River, low temperature
- Pseudanabaena yagii
ASJC Scopus subject areas
- Microbiology (medical)