Résumé
The influence of nitrogen source (nitrate, ammonium, nitrate and ammonium, glutamine) on growth of Cortinarius orellanus (isolate L6) and on accumulation of nitrogen and phosphorus in the mycelium was studied in vitro. Growth was poorest on nitrate which showed no significant accumulation, as in other Homobasidiomycetes previously studied. Soluble organic nitrogen and amine nitrogen accumulated in greater quantities (μmol N per mycelium) and concentrations (μmol N g−1d.w.) on nitrate medium. The relative proportions of insoluble nitrogen with respect to total nitrogen reached 75 and 40% on ammoniacal and nitric media, respectively. This results from those obtained in other Homobasidiomycetes and in most of the cultivated Phanerogams. This could reflect differences in ways of assimilating ammonium in vascular plants and indicates the role of ammonium in the enzymatic mechanisms that regulate amino-acid synthesis. The mean concentrations of total phosphorus varied from 0.8 to 0.9% of the dry weight of the mycelium.