ESSENTIAL METALLIC ELEMENTS 81 



Within limits, the growth of M. aUiaceus and M. epiphyllus was propor- 

 tional to the concentration of either of these elements, and the response 

 to each element was modified by the presence of the other. The data in 

 Table 14 illustrate this effect. 



In addition to the essential micro elements discussed above, there is 

 some evidence which indicates the essentiality of other metallic elements 

 for the fungi. Certain of these elements are essential for other organisms. 



Gallium. Under certain conditions Steinberg (1938) was able to show 

 that omission of this element from the medium led to decreased yield and 

 sporulation of Aspergillus niger. Extraordinary care was needed to 

 demonstrate gallium deficiency. The chemicals used were spectroscopi- 

 cally pure with the exception of traces of iron, calcium, and sodium. The 

 sucrose, after 6-hr. extraction with alcohol, contained only 0.0014 per cent 

 ash. The water used was triple-distilled, the last distillation being made 

 in a quartz still. Spectroscopically pure calcium oxide w^as used to purify 

 the sucrose further. Under these conditions the yield of A. niger 

 increased from 814 mg. to 1,053 mg. when gallium (0.02 mg. per liter) was 

 added to the medium. The salts of 76 other chemical elements were 

 tested, and none was found to replace gallium. In view of the similar 

 chemical behavior of gallium and aluminum, Steinberg considers it possi- 

 ble that the biologic activity sometimes attributed to aluminum may in 

 reality be due to gallium. 



Scandium. In the discussion of the role of manganese in nitrogen 

 metabolism it w^as noted that the amount of manganese required was 

 determined by the nitrogen source used. In a somewhat similar fashion, 

 Steinberg (1939) found that scandium appeared to be essential when 

 glycerol was used as a carbon source for Aspergillus niger. Growth was 

 poor on this carbon source ; omission of copper or manganese increased the 

 yield somewhat. Omission of scandium decreased the yield from 269.4 to 

 107.4 mg. Interestingly enough, scandium appeared to have no effect on 

 growth when sucrose was used as a source of carbon. Addition of lysine 

 or proline (20 mg. per liter) to the glycerol medium increased growth and 

 at the same time prevented the effect of scandium. These results suggest 

 that the need for certain elements may be shoA\Ti only under certain 

 nutritional conditions. 



Vanadium. Bertrand (1943) reported the presence of this element in 

 all fungi examined. Amanita muscaria contained from 61 to 156 mg. of 

 vanadium per kilogram. Bertrand (1941) considers vanadium as an 

 essential element for Aspergillus niger. 



Cobalt. Whether fungi require some, or all, of the other metallic ele- 

 ments required by other organisms is not kno^vn. Cobalt is required by 

 animals. Lack of sufficient amounts of this element in the soil causes 

 severe cobalt deficiency in animals which are pastured on such soils. 



