226 ' PROTEIN (NITROGEN) METABOLISM OF BACTERIA 



the energy supplied by the reactions. Some of the nitrate nitrogen may of course be 

 used for cell structure. 



It has been claimed that the entire oxidation process may be brought about by a 

 single organism, but evidence on this point is still quite meager. 



The subjects of utilization of free atmospheric nitrogen, and of nitrification and 

 denitrification, are dealt with only very briefly in this chapter because they are dis- 

 cussed at some length in other chapters of this volume. 



