A musty odor problem occurs at water purification plant (WPP) of Yokohama WWB since 2016. The odor compound that causes the problem is 2-methylisoborneol (2-MIB). The maximum value of 2-MIB concentration detected in raw water was 54 ng/L in July 2018. This 2-MIB is considered to be released as a metabolite of periphytic filamentous cyanobacteria in biofilms adhering on pebbles in the water source river. Because of the adhering, it is hard to detect the cyanobacteria in the raw water even with a high 2-MIB concentration detection. Therefore, there is almost no way to evaluate the relationship between the cyanobacteria proliferation and 2-MIB detections, and it is difficult to keep up controlling the water with the odor of 2-MIB at WPP. To investigate on the relationship, we sampled the biofilms on site, isolated and cultured. There were cultured cyanobacteria strains whose morphological taxonomy classification were the same, but whose 2-MIB detections were different. In this study, to screen the cyanobacteria as 2-MIB producers and non-producers, we successfully establish two test methods; 1) a 2-MIB gene detection method with two primers, a 2-MIB gene as the target gene primer and a ribosomal 16S rRNA gene as the reference gene primer, and 2) a phylogenetic classification method with Internal Transcribed Spacer (ITS) region of the ribosomal gene primer is to classify the cyanobacteria on the difference of the 2-MIB produce capability. These methods will be useful tools for screening the cyanobacteria on 2-MIB producing for development of a better water treatment management.

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[in Japanese]

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