ORGANIC NUTRIENTS OF FUNGI 23 



[Wolf and Shoup (1943)]. Similarly, Wolf and Shoup found 

 that A. jcruanicus employs peptone, aspartic acid, asparagine, cys- 

 tine, and glutamic acid; whereas A. moniliformis and A. cysto- 

 genus utilize only peptone, alanine, aspartic acid, and glutamic 

 acid. None of these species was able to use the amino acids gly- 

 cine and tyrosine. 



Nielsen and Hartelius (1938) grew yeast in beer wort, with 

 added thiamin, as a basic medium and then added /2-alanine, aspara- 

 gine, aspartic acid, lysine, and arginine singly and in combina- 

 tions. They found that alone each was toxic but that growth was 

 improved when all were added. 



Claims that certain fungi employ NH 4 + to the exclusion of all 

 other nitrogen sources and therefore may be called "ammonia or- 

 ganisms" are not fully supported. Among other factors account 

 has not been taken generally in these studies of the influence of 

 pH. This subject was given special consideration by Rippel 

 (1931). Pirschle (1934) found that ammonia organisms will uti- 

 lize NO3"" provided that the cultures are aerated. This fact is 

 shown by certain of his data that contrast the weight of yeast 

 in nonaerated and aerated cultures. With ammonium sulphate, 

 the dry weights in nonaerated and aerated cultures were 2.568 

 and 6.348 grams, respectively; with calcium nitrate 0.703 and 8.089 

 grams, respectively; with potassium nitrate 0.443 and 5.296 grams, 

 respectively. Smaller growth from the nitrates than from the 

 ammonium nitrogen may be accounted for by HN0 2 formation, 

 since the consensus of opinion is that nitrites are toxic. Removal 

 by aeration of this toxic effect in Pirschle's cultures is evidence 

 that this hypothesis is valid. 



Whether any fungi are entitled to be grouped among the nitro- 

 gen fixers has been the subject of much controversy. In 1892 

 Frank [Duggar and Davis (1916)] maintained that Hormoden- 

 dron cladosporioides, grown on -nitrogen-free media, fixes nitro- 

 gen. The following year Berthelot made a similar claim [Duggar 

 and Davis (1916)] for Aspergillus niger and Alternaria tenuis. 

 The same ability was attributed to fhoma betae, A. niger , and 

 Mucor stolonijer by Saida in 1901 [Duggar and Davis (1916)]. 

 Latham (1909), working with A. niger, also reported the fixation 

 of appreciable quantities of nitrogen, but Pennington (1911) was 

 unable to verify her observations. 



