THE UTILIZATION OF NITROGEN COMPOUNDS, ESPECIALLY AMMONIA, BY A LOW-TEMPERATURE BASIDIOMYCETE

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Abstract
The nitrogen nutrition of a low-temperature basidiomycete, a cause of snow mold in Western Canada, was studied in submerged culture. L-Glutamine, L-asparagine, a number of amino acids, and urea supported excellent growth in a glucose – mineral salts medium supplemented with thiamine and pyridoxine, while several amino acids, acetamide, ethylamine, and methylamine were not utilized. D-Asparagine was not utilized, D-aspartic acid was utilized to a limited extent, while D-alanine supported as much growth as L-alanine. Nitrate and nitrite were not utilized and in initial experiments ammonium salts supported only limited growth, their utilization being accompanied by a rapid fall in the pH of the medium to inhibitory levels. Subsequently ammonium salts were found to be excellent sources of nitrogen provided the pH was controlled either by titration or by the inclusion of organic acids in the medium. A number of organic acids were found to be effective and, in general, their effectiveness was correlated with their buffering capacity within the pH range 3 to 6. Although pyruvic and α-ketoglutaric acids were taken up during growth it seemed improbable that they participated directly in ammonia utilization. With ammonium chloride as nitrogen source, changes in the pH, ammonia, total, and amino nitrogen levels were followed throughout growth when pyruvic acid, α-ketoglutaric acid, L-alanine, or L-glutamic acid were added to the medium. The results again indicated that pH was the main factor controlling growth. They also demonstrated that amino nitrogen is utilized for growth far more efficiently than ammonia nitrogen.