MINERAL NUTRITION OF FUNG! 11 



TABLE 4 



Elements Shown to Be Present by the Use o? Spectroscopic Methods 



of Analysis 



Chemical Reagents Contaminants 



NH4NO3 Ca, K, Mg, Na 



K2HPO4 Al, Ag, Cu, Mg, Na, Pb 



MgS0 4 -7H 2 Cu, Na 



ZnS0 4 -7H 2 As, B(?), Cu, Fe, Mg, Mn, Si, Sn(?) 



CuS0 4 -5H 2 Cu, Fe, Mg, Mn, Pb, Si 



MnS0 4 -2H 2 Al, Ca, Cu, Cr, Fe, Mg, Na, Si, V 



Na 2 Mo0 4 Al, Ca, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Si, V(?) 



Dextrose Al, Ag, B, Ca, Cu, Fe, K, Li, Mg, Mn, Na, Ni, 



Rb, Rh, Si, Sn, Sr 



metals to be precipitated as phosphates, hydroxides, or carbonates. 

 In some cases Mo;C03 may be substituted for heating;. 



Bortels (1927) and Roberg (1928) used activated charcoal as 

 an adsorbing agent after adding (NH 4 ) 2 S as a precipitant. Some 

 heavy-metal contaminants may be removed bv electrolysis. Wolff 

 and Emmerie (1930) removed copper from their nutrient salts by 

 electrolytic methods. 



The spores of Aspergillus oryzae were found by Aso (1900) 

 to have iron among their ash constituents. Copper and doubtless 

 other metals as well occur in the spores and mycelium of other 

 fungi. These observations show that in studies involving the min- 

 eral nutrition of fungi an appreciable metal contamination may be 

 attributed to the inoculum. 



Steinberg (1935) determined that the quantity of the elements 

 essential for optimum growth of Aspergillus niger is 0.20 mg of 

 iron, 0.14 mg of zinc, 0.06 mg of copper, and 0.03 mg of manga- 

 nese per liter of solution. The amount of growth was approxi- 

 mately doubled with as little as 0.001 mg of zinc per liter. 



The weight of evidence indicates that these metal contaminants, 

 especially zinc, copper, iron, and manganese, serve in the nutrition 

 of fungi, not as structural materials, but as substances that modify 

 physiological activities. For this reason they have come to be re- 

 garded as biocatalysts. This conception is fostered by the numer- 

 ous publications of Bertrand and of Javillier, which are reviewed 

 by Foster (1939), and by the papers of Bortels (1927), Steinberg 

 (1934), and Stern (1938). The heavy metals become organic 

 components of respiratory enzymes. Stern (1938) has stressed 



