Improved media for growth and sporulation of Sporidesmium sclerotivorum

Abstract

Additional nutritional and environmental factors affecting growth and sporulation of the beneficial mycoparasite, Sporidesmium sclerotivorum, were determined. A liquid medium composed of mineral salts, glucose, glutamine, thiamine, biotin, and succinic acid supported good growth and sporulation of isolate CS-5 within 5 weeks at 25 °C. Growth was substantially greater in a medium with KH2PO4, CaCl2, minor elements, and ferric–potassium salt of EDTA (FeKEDTA) than in media with single omissions of these ingredients. Iron supplied as FeCl3 or FeKEDTA at 10−5 M or greater markedly stimulated production of conidia. Supplementation of the medium with Casamino acids or with Soytone and yeast extract decreased the lag phase slightly but did not affect the maximum growth rate nor final mycelial and spore yield. Succinic acid (0.2%) buffered the medium against a rapid drop in pH and thereby promoted growth. The growth rate was independent of glucose concentrations of 0.5 to 2%, but the total mycelial yield was dependent upon the total amount of glucose furnished. Conidia developed primarily on mycelial mat surfaces, and maximum spore yields were favored by cultivation in shallow depths of medium.