126 



THE ACTINOMYCETES, Vol. I 



1939; Erikson, 1949), and other long-chain 

 carbon compounds (Webley and de Kock, 

 1952). This property is usually associated 

 with oxidative metabolism, potential acid- 

 fastness, production of red or orange pig- 

 ments of the carotenoid type, and lack of 

 diastatic and proteolytic enzymes. The 

 saprophytic strains, with yellow, greenish, 

 or no pigments (Jensen, 1931-1932; Krassil- 

 nikov, 1938; von Plotho, 1948), seem to be 

 devoid of acid-fastness and fail to utilize 

 paraffin, but they are more fermentative 

 and often show diastatic and proteolytic 

 effect. 



Nitrogen Nutrition 



Proteins, peptones, and certain amino 

 acids form the best sources of nitrogen for 

 actinomycetes, followed by nitrates, am- 

 monium salts, and urea. Actinomycetes are 

 unable to fix nitrogen and have to depend, 

 like the great majority of fungi and bacteria, 

 upon fixed compounds of nitrogen for their 

 cell synthesis. 



Miinter (1914) made one of the first de- 

 tailed studies of nitrogen utilization by cer- 

 tain actinomycetes, now recognized as 

 streptomyces. Lieske (1921) used a 2 per 

 cent glucose solution containing a small 

 amount of MgS04 and K2HPO4 , and 1 per 



Table 27 



Nitrogen ulilization by different actinomycetes 

 (Lieske) 



Table 28 

 Utilization of different amino acids by a strepto- 

 myces as compared to that of a fungus 

 (Wak.sman and Lomanitz) 



cent of the various nitrogen sources. Incuba- 

 tion took place at 37°C (Table 27). Lieske 

 recognized that had other species and other 

 conditions of growth been used, different 

 results would no doubt have been obtained. 



Fedorov and Iliina (1956) have shown 

 that nitrates and nitrites are excellent forms 

 of nitrogen for various actinomycetes. They 

 are reduced down to ammonia and as- 

 similated for all syntheses. The reduced 

 forms of nitrogen (ammonia and hydroxyl- 

 amine) are also readily utilized, but in lower 

 concentrations. Organic nitrogen sources 

 (urea, amino acids, peptone) are utilized 

 even more readily. Cell synthesis, however, 

 is low, not exceeding 10 to 12 per cent, when 

 the ratio of C:X is less than 20:1 in the 

 organic substrate, free ammonia accumu- 

 lates. The nitrogen content of the mycelium 

 varies with the ratio of carbon to nitrogen 

 in the substrate. 



The great majority of actinomycetes be- 

 longing to the genus Streptomyces are able 

 to liquefy gelatin and utilize casein. The 

 nocardias, as a rule, are unable to do so. 

 ]\Iany of the actinomycetes are able to co- 

 agulate and later peptonize milk, though 

 peptonization fre{iuently occurs without 

 previous coagulation. Blood serum is li(iue- 

 fied by many streptomyces. Complex pro- 

 teins, such as hoof meal and horn meal, can 

 also be attacked by certain forms, such as 

 S. fradiae. 



