22 NUTRITION OF FUNGI 



any or all of the other forms. On this basis it appears that fungi 

 must be regarded as differing among themselves fundamentally in 

 metabolic potentialities as far as usage of nitrogen is concerned. 



It might be anticipated that amino acids would constitute the 

 nitrogen form of first choice for the reason that they can be 

 utilized in the synthesis of proteins with the least need for energy. 

 Evidently, how ever, there are other factors involved in the choice 

 of nitrogen. At anv rate, amino acids are well suited to a large 

 number of fungi, and Bacto-peptone serves well as a source for 

 many species. Boas (1919) interpreted his experiments to show 

 that amino acids can be used only after they have been deaminized. 

 In this process energy is required, and Boas regarded ammonium 

 salts as the most suitable nitrogen source, they being much superior 

 to peptones. 



In general there is a paucity of convincing experiments on the 

 best source of nitrogen for specific fungi. In their trials with 20 

 plant pathogens Young and Bennett (1922) found that each spe- 

 cies could utilize nitrate nitrogen; thus they fall into the third 

 of the groups proposed by Robbins. In 1910 Hagem [Steinberg 

 (1939a)] noted that Mucor cbristianensis, M. griseocyamis, M. 

 racemosas, M. sphaerospora, and M. spinosus utilize either NH 4 + 

 or NOr with glycerol. Aspergillus fischeri, according to 

 Wenck, Petersen, and Fred (1935), uses either NH 4 + or organic 

 nitrogen, thus falling into the second of Robbins' groups. Ophio- 

 bohis graminis requires organic nitrogen [Fellows (1936)], and 

 Basidiobolus ranarum and Saproleguia parasitica need amino acids 

 [Leonian and Lilly (1938)]. Leonian and Lilly also used 23 other 

 organisms in tests in which various amino acids, singly or in com- 

 binations, were substituted for ammonium nitrate, they did not 

 obtain any evidence of ability to utilize these amino acids. If they 

 added thiamin (vitamin Bi), however, proper amino acids induced 

 growth in 14 of the 23 species. Observations by Klotz (1923) 

 showed that Aspergillus viger, Diplodia uatalensis, and Spbae- 

 ropsis vialorum can utilize amino nitrogen. Neither Apodachlya 

 brachynema nor Leptomitus lacteus is able to utilize nitrate nitro- 

 gen or ammonia, but both find rf, /-alanine and /-leucine suitable 

 for growth and, if acetate is present, utilize also glycine and 

 asparagine [Schade (1940)]. 



Alloviyces arbuscula makes use of peptone, alanine, aspartic 

 acid, asparagine, arginine-HCl, cystine, glutamic acid, and leucine 



