PRELIMINARY REPORT ON SYNTHETIC MEDIA 137 



property of the enzyme no doubt regulates the abihty of the 

 parent cell to utilize a compound, consequently, organisms can 

 utilize as a source of energy and carbon for cell construction 

 only those compounds whose configuration, or the configuration 

 of a radical therein, matches the configuration of their enzymes. 

 By commencing with the simplest carbon compounds capable 

 of yielding energy we may, by admitting only one energy ma- 

 terial at a time build up a series of synthetic media which are 

 mutually inclusive and exclusive. That is, those organisms 

 which have an enzyme in common can utilize a given compound, 

 while those which do not possess the necessary enzyme will 

 not develop, providing the compound is not too complex; other- 

 wise, some of the decomposition products may have a suitable 

 configuration. We find that carbon compounds having a cer- 

 tain configuration or certain atomic groups can be utilized by 

 all those microorganisms which develop the requisite enzyme. 

 Therefore, as far as energy is concerned, it is possible to prepare 

 a medium w^hich will allow the growth of only a given number of 

 organisms. 



Numerous investigators have shown that bacteria as well 

 as molds can utilize ammonia nitrogen. Gerlach and Vogel 

 isolated and studied several forms of bacteria which were capable 

 of utilizing nitrate nitrogen. It is a well known fact that a 

 large number of molds also readily assimilate nitrate nitrogen. 

 Renato Perrotti pointed out the fact that certain bacteria were 

 capable of utilizing cyanide nitrogen. The assimilation of 

 either ammonia, nitrate or cyanide nitrogen was dependent, 

 always, upon the presence of suitable energy materials. 



Previous work indicates that the other nutrient elements 

 necessary, for bacteria at least, are probably common to all, 

 therefore, the development of synthetic media must follow 

 two lines of cleavage — first, according to carbon compounds 

 required for energy, and second, according to nitrogen compounds 

 required for nutrition. 



In order to make the resume complete we need only men- 

 tion those bacteria which require a source of carbon for energy 

 and utihze free nitrogen, those which obtain their energy by the 



