METABOLISM OF ACTINOMYCETES 



13 



or only traces of nitrites with all sources of carbon studied; 

 while most organisms vary in their power to reduce nitrates to 

 nitrites with the source of carbon in the medium. 



Different suggestions have been made concerning the physi- 

 ological importance of nitrate reduction for the bacterial cell. 

 A complete discussion of this subject can be found in the work 

 of Klaeser (1914). He refuted various theories on this subject 



TABLE 2 

 Reduction of nitrates to nitrites as affected by different sources of carbon 



and concluded that the reduction of nitrate to nitrite and am- 

 monia by bacteria is a process by which these bacteria cover 

 the nitrogen need in their metabolism. This conclusion of 

 Klaeser in regard to bacteria is fully confirmed by the study of 

 the metabolism of actinomycetes. These organisms reduce the 

 nitrates to nitrites, in the process of utilization of this nitrogen 

 compound, but not for any other purpose. This reduction is 

 brought about by hydrogen, as shown by several investigators 

 (Klaeser, 1914). The importance of this phenomenon in rela- 

 tion to the change of reaction of the medium will be discussed 

 in the following paper of this series. 



