SUMMARY: The pathways for syringic acid metabolism have been studied in detail for the white-rot fungus Sporotrichum pulverulentum and a reaction sequence proposed. According to identified metabolites the following reactions occur: reduction of the carboxyl group; hydroxylation and simultaneous decarboxylation; demethylation; and methylation of the p-hydroxyl group. In the two soft-rot fungi Petriellidium boydii and Phialophora mutabilis rapid metabolism of syringic acid was observed and the medium was depleted of the acid within 12 h. The formation of 3,4,5-trimethoxybenzoic acid indicates an ability within the soft-rot fungi also to methylate the p-hydroxyl group. The two brown-rot fungi Daedalea quercina and Fomes pinicola were poor metabolizers of syringic acid. However, demethylation was observed with F. pinicola and an unidentified product appeared in the culture solution of D. quercina.
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