4 NUTRITION OF FUNGI 



Sulphur requirements. The results obtained with these nu- 

 trient solutions make a voluminous literature. There appears 

 little reason to doubt that these experiments prove the essentiality 

 for all fungi of appreciable amounts of potassium, phosphorus, 

 magnesium, and sulphur. Inorganic phosphates constitute en- 

 tirely satisfactory sources of potassium and phosphorus. Mag- 

 nesium sulphate serves well as the source of magnesium, but not 

 all fungi are able to use sulphates as a source of sulphur. Arm- 

 strong (1921) observed that persulphate, sulphite, and sulph- 

 hydryl can be substituted for sulphates in the nutrition of Asper- 

 gillus ?iiger, Penicillium glaucum, and Botrytis cinerea. Volkon- 

 sky (1933, 1934) made similar observations with certain water 

 molds, such as Achlya, Aphanomyces, Dictyuchus, Isoachlya, and 

 Leptolegnia, and pointed out that each of these forms grows 

 better on organic than on inorganic sulphur compounds. The 

 results for inorganic sulphur were substantiated by Leonian and 

 Lilly (1938), whose experiments show that the amino acid /-cys- 

 tine is necessary for the growth of Saprolegnia mixta, Achlya 

 conspicua, Aphanomyces camptostylus, and Isoachlya ?nonilifera. 

 Schade (1940), on the other hand, found that Leptomitus lac- 

 teas and Apodachlya brachynema fill their sulphur requirements 

 by reducing sulphates. Steinberg's (1941) experiments show that 

 Aspergillus niger utilizes both organic and inorganic sulphur. Of 

 the organic sulphur compounds, alkyl sulphonates and alkyl sul- 

 phinates are readily assimilated, but the alkyl mercaptans, sul- 

 phides, and disulphides are not utilized. In the case of inorganic 

 sulphur compounds, the sulphur is first reduced to sulphoxalate 

 and then converted to organic sulphur. 



Calcium requirements. Whether calcium is essential for all 

 fungi is still a controversial question that should be studied, the 

 best techniques known for such tests being utilized. Molisch 

 (1894) came to the conclusion that fungi do not require calcium. 

 Mosher et al. (1936) have presented evidence to show that Tri- 

 chophyton inter digitale requires calcium. Young and Bennett 

 (1922) concluded that calcium is generally beneficial in the 

 growth of most fungi and is certainly required by Fiisariinn 

 oxysporum, Rhizopus nigricans, and Aspergillus niger. They 

 also grew species of Ascochyta, Botrytis, Cercospora, Colleto- 

 trichum, Dothiorella, Alacrosporium, Phoma, Rhizoctonia, Sclero- 



