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 untreate d controls, suggesting a possible inhibition of reactions prior to ses quiterpenoid biosynthesis. However, exposure to clomazone increased ge osmin accumulation in S. tendae cultures grown on Hickey-Tresner mediu m and in cultures of the fungus Penicillium expansum. Additionally, cl omazone increased accumulation of a sesquiterpenoid tentatively identi fied as a eudesmol in S. tendae, indicating possible point(s) of inhib ition subsequent to sesquiterpenoid biosynthesis. Geosmin biosynthesis was induced by transferring cultures of S. tendae inoculated on Actin omyces medium to Hickey-Tresner medium 24 h after inoculation. When ha rvested at 48 h, geosmin biosynthesis-induced-cultures exposed to clom azone contained more geosmin than untreated controls, indicating that response of a single taxon to clomazone can be rapidly altered by chan ging medium composition.