Studies on the Nutrition of Morchella Esculenta Fries

SUMMARY

There has been very little work done on the physiology of fleshy Ascomycetes. Morchella esculenta, because of its possible role as a food mushroom, is of much general interest and it would be highly desirable to have basic nutritional studies done on it. The present paper presents the beginnings of such a study.

M. esculenta will grow on agar or in liquid culture on synthetic media composed of mineral salts and suitable carbon or nitrogen sources. A survey of many such carbon and nitrogen sources was made. The organism grew well on starch, maltose, fructose, turanose, glucose, and sucrose and moderately well on several others. Polyhydric alcohols and levorotatory methyl sugars supported little growth. Inulin was utilized in growth on agar but not in liquid culture.

As nitrogen sources, cysteine-HCl, aspartic acid, asparagine, urea, sodium nitrite, various ammonium salts, alanine, glutamic acid-HCl, and sodium nitrate were favorable. Other amino acids and nitrogen compounds were intermediate or poor. Ammonium citrate, thiourea, hydroxylamine-HCl, and hydrazine-2HCl were toxic.

The pH-growth curve for this organism was bimodal, with maxima at pH 6.93 and 8.3 and a minimum at 7.45. Optimum pH for growth was at pH 6.93, which is unusually high for fungi. The bimodal curve is attributed to the effect of pH on the fungus isoelectric point; the minimum point at pH 7.45 is interpreted as the isoelectric point for the cell colloids.

Apparently pH, carbon source, and other factors influence the utilization of nitrogen compounds.

These results are discussed from the standpoint of the experimental techniques required in a nutritional study and of the various general aspects of fungus physiology.