EFFECTS OF CLOMAZONE ON BIOSYNTHESIS OF GEOSMIN BY STREPTOMYCES-TENDAE AND PENICILLIUM-EXPANSUM

Cultures of Streptomyces tendae grown on Actinomyces medium containing clomazone contained less geosmin 48 h after inoculation than untreated controls, suggesting a possible inhibition of reactions prior to sesquiterpenoid biosynthesis. However, exposure to clomazone increased geosmin accumulation in S. tendae cultures grown on Hickey-Tresner medium and in cultures of the fungus Penicillium expansum. Additionally, clomazone increased accumulation of a sesquiterpenoid tentatively identified as a eudesmol in S. tendae, indicating possible point(s) of inhibition subsequent to sesquiterpenoid biosynthesis. Geosmin biosynthesis was induced by transferring cultures of S. tendae inoculated on Actinomyces medium to Hickey-Tresner medium 24 h after inoculation. When harvested at 48 h, geosmin biosynthesis-induced-cultures exposed to clomazone contained more geosmin than untreated controls, indicating that response of a single taxon to clomazone can be rapidly altered by changing medium composition.