Carbon and Nitrogen Nutrition of Sclerotium Cepivorum

SUMMARY

Several monosaccharides (glucose, galactose, mannose, fructose), di-and trisaccharides (cellobiose, sucrose, raffinose, maltose), and polysaccharides (inulin, starch, dextrin, glycogen) were excellent carbon sources for growth and production of sclerotia of Sclerotium cepivorum. Inulin and soluble starch were exceptionally good sources of carbon for production of sclerotia by several isolates of the fungus. Pectic substances, gluconic acid, and sorbitol were utilized slightly for growth. Several carbohydrate derivatives and Krebs cycle intermediates were not utilized. Casein hydrolysate, vitamin-free casamino acids, NaNO₃, NH₄Cl, the amino acids isoleucine, arginine, proline, aspartic acid, leucine, and the amides asparagine and glutamine were the best nitrogen sources for growth. Valine, lysine, serine, glycine, histidine, and threonine were not utilized for growth. Proline, arginine, histidine, casein hydrolysate, and glutamine were the only nitrogen sources that allowed production of sclerotia by all isolates tested.

Optimum temperature range for growth of S. cepivorum was 15–20 C, and the fungus grew better at 10 than at 25 C. The optimum concentration of carbon/liter from glucose depended on the isolate used. For one isolate, growth increased linearly with an increase of glucose carbon from 0 to 20.0 g/liter. Two g of nitrogen/liter from L-proline or NaNO₃ was the optimum concentration for growth. High concentrations of L-proline in the medium (more than 0.25 g nitrogen/liter) supported excellent production of sclerotia by three isolates.