Characterization of Oscillatoria F. Granulata Producing 2-methyl-isoborneol and Geosmin

Abstract

We characterized the cyanobacterium Oscillatoria f. granulata isolated from water collected from a cooling tower in Tokyo, Japan. The O.f.granulata produced the earthy/musty odor-producing substances geosmin and 2-methylisoborneol (2-MIB). Chlorophyll a and the levels of both odor compounds were markedly increased at 1000 lux compared to those at 500 and 2000 lux illumination. After a 40-day incubation, 338g/l of 2-MIB and 5.9g/l of geosmin were found in the No.11 culture medium. With incubation in CT liquid medium, a level of 2-MIB that was 3.1 times higher than that in the No.11 culture medium was obtained. Metabolites in the culture of O.f.granulata were identified using atomic emission detector-gas chromatography (AED-GC) and gas chromatography/mass spectrometry (GC/MS). The AED-GC analysis revealed many peaks containing C, H, O atoms as well as 1 peak of nitrogen on the GC chromatogram, but there were no chlorine-, bromine- or sulfur-containing peaks. The GC/MS analysis identified 6 terpenoids (e.g., eudesmol and sesquiterpene alcohols), 3 phenols (e.g., phenol and BHT), 6 aldehydes (e.g., nonanal, decanal and undecanal), 8 fatty acids (e.g., penta-, hexa- and octadecanoic acid), 8 hydrocarbons (e.g., n-heptadecane, methyl heptadecane and octadecane) and phytol.