Induction of Secondary Metabolism by Environmental Pollutants: Metabolization of Pyrene and Formation of 6,8-Dihydroxy-3- methylisocoumarin by Crinipellis stipitaria JK 364
2014
Lange, Bettina | Kremer, Stefan | Sterner, Olov | Anke, Heidrun
In submerged cultures, when grown in the presence of pyrene. the saprophytic and plant inhabiting basidiomycete Crinipellis stipitaria was found to produce 6,8-dihydroxy-3-methyl-isocoumarin. The amount of 6,8-dihydroxy-3-methylisocoumarin formed depended on the concentration of pyrene in the medium. In cultures incubated without pyrene or with less than 2.5 mg/l no formation of 6,8-dihydroxy-3-methylisocoumarin was observed. Besides pyrene, chrysene, another four ring polycyclic aromatic hydrocarbon, induced isocoumarin formation whereas anthracene, phenanthrene or fluoranthene were not effective. During metabolization experiments with [4,5,9,10-¹⁴C]pyrene (0.4 mCi (14.8 kBq)/mmol), labelled 6.8-dihydroxy-3-methylisocoumarin (specific activity 15 μCi (0.6 kBq)/mmol) was isolated, in addition labelled acetic acid (specific activity 0.1 μCi (4 Bq)/mmol) was identified. When C. stipitaria JK 364 was incubated for 14 days with 5 μCi (0.2 kBq) sodium [2-¹⁴C]acetate and 10 mg/l pyrene. labelled 6.8-dihydroxy-3-methylisocoumarin was isolated from the culture. The results are in agreement with the polyketide origin of the isocoumarin and proof the breakdown of pyrene to acetate which is a central intermediate in the pathway from pyrene to 6,8-dihydroxy-3-methylisocoumarin.
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