242 PRINCIPLES OF SOIL MICROBIOLOGY 



The ammonium salts can be used in the form of phosphate, sulfate, 

 chloride and salts of organic acids, like acetic, tartaric and citric, in 

 concentrations of 0.1 to 0.5 per cent. ■ Ca, K, and Na nitrates can be 

 used by almost all Aspergillaceae and various other fungi. 32 Among 

 the organic nitrogenous compounds, peptone and amino acids (as- 

 paragine, leucine, etc.), followed by amides, amines, and alkaloids, 33 

 are found to be favorable sources of nitrogen. 



Carbohydrates and higher alcohols are the best sources of carbon; 

 of these, glucose comes first, followed by other hexoses and pentoses. 34 

 Sucrose is utilized only by fungi which can produce invertase; when 

 added to an acid medium, it is inverted in the process of heating. 

 Starch is utilized only by fungi which can produce diastase. It is 

 employed either in the form of a paste or as soluble starch. Pectins are 

 also used as sources of energy by various fungi. 35 Celluloses can be 

 decomposed by certain fungi, hence mold activity is of great importance 

 in the decomposition of organic matter in the soil. Of the alcohols, 

 glycerol and mannite are used most readily; the lower alcohols only in 

 dilute solutions. Of the organic acids, those having more carbon 

 atoms, like tartaric, citric, and malic, are best. Some fungi can utilize 

 fats as sources of energy. 36 



Of the mineral elements, K, Mg, S, and P are necessary and cannot 

 be replaced by others. If required Ca, Na, CI need be present only in 

 traces; Fe as well is sufficient in mere traces, when needed. Cu, Zn 

 and Fe can act as stimulants. 



The following media can be used for the cultivation of the great 

 majority of soil fungi: 



32 Blochwitz, A. Vergleichende Physiologie der Gattung Aspergillus. 

 Centrbl. Bakt. II, 39: 499-502. 1913; Kossowitz. Biochem. Ztschr., 67: 400. 

 1914. 



33 Ehrlich, F. t)ber einige chemische Reaktionen der Mikroorganismen und 

 ihre Bedeutung fur chemische und biologische Probleme. Mitt, landw. Inst. 

 Breslau, 6: 705-713. 1912; (Centrbl. Bakt. II, 41: 245-246. 1914). 



34 Peterson, W. H., Fred, E. B., and Schmidt, E. G. The fermentation of 

 pentoses by molds. Jour. Biol. Chem., 55: 19-34. 1922. 



36 Hauman, 1902 (p. 203); Behrens, 1903 (p. 203). 



36 Spieckermann, A. Mykologie der Kraftfuttermittel. Lafar's Handb. 

 techn. Mykol., 2: 361-388. 1907; Ztschr. Unters. Nahr. Genuszm., 27: 83. 

 1914; Rahn, O. Die Zersetzung der Fette. Centrbl. Bakt.. II, 15: 422-429. 

 1906. 



