抄録
Six strains (A, C, F, F, I and J) of Actinomycetes which produced musty odor were isolated from the water and sediments of Lake Kasumigaura. All of six strains were identified as Streptomyces by morphological and taxonomical studies. All strains produced 2-methylisoborneol, and geosmin was produced by only four strains.
Various environmental conditions for musty odor production under the same nutrient concentrations as Lake Kasumigaura water were investigated. The musty odor production was measured by sensory test. The values of threshold odor number were highly correlated to the 2-methylisoborneol and geosmin concentration, respectively. Threshold odor number of 1 for 2-methylisoborneol and geosmin corresponded to 0.007μg/l and 0.01μg/l. The optimum temperature and pH for the musty odor production were 25°C and between 8 and 9. The water of Lake Kasumigaura contained sufficient amount of nutrients to produce intense musty odor with respect to nitrogen, phosphorus, iron and magnesium. Carbohydrates as carbon sources were more effective to the musty odor production than organic acids and amino acids. It was considered that highly musty odor were produced by Streptomyces when adequate carbon sources did exist in Lake Kasumigaura water.
