Expression of pisatin demethylating ability in Nectria haematococca

A mycelial suspension of Nectria haematococca completely demethylated 0.1 mM pisatin in 2 h in a medium free of other carbon sources while no demethylation of pisatin by the fungus occurred in 6 h when 2% glucose was in the medium. Prior exposure of the fungal cells to pisatin in glucosefree medium markedly enhanced the rate of pisatin demethylation, with maximum stimulation occurring 5–9h after the initial exposure. The stimulation of pisatin demethylating ability was relatively specific for pisatin as the inducer. Out of a large variety of isoflavonoids tested the only compounds other than pisatin that stimulated the activity significantly were pterocarpan or isoflavan derivatives. Protoplasts with pisatin demethylating ability were isolated from pisatin-treated mycelium. Attempts to obtain a cell-free system with pisatin demethylating ability from these protoplasts were unsuccessful.