ENERGY SUPPLY OF THE CELL 61 



Really, the process must occur in two steps, one being 

 the hydrolysis, and the other being the neutralization 

 of the ammonia and the carbonic acid formed. 



CO(NH2)2 + 2H2O = CO3H2 + 2NH3 



CO3H2 + 2NH3 = (NH4)C03 



Sohngen (1909) has proved that urea is entirely 

 sufficient as a source of energy for urea bacteria, and also 

 as a source of nitrogen for cell construction, but not as a 

 source of carbon. 



While urea is fermented by a large number of species 

 from different genera and families, uric and hippuric 

 acid are fermented mostly by spore formers. The hip- 

 puric acid is hydrolyzed into benzoic acid and glycine : 



CeHsCO-NH-CHz-COOH = CeHsCOOH + 



NH2CH2COOH 



Uric acid is split into its natural components, two 

 molecules of urea and one of a tri-carbon compound 

 which is readily oxidized. 



Prototrophic Fermentations. — A large number of 

 prototrophic fermentations are known, all of which 

 are oxidations. The largest number of species occur 

 in the sulphur bacteria which oxidize H2S primarily 

 to S, and later to H2SO4. While all members of 

 this very large group behave ahke in their energy 

 acquirement, the bacteria acting upon ammonia have 

 clearly divided their task, as the one group can only 

 oxidize ammonia to nitrite, and the other only nitrite 

 to nitrate; not ammonia to nitrate. 



The other various oxidations of methane and higher 

 hydrocarbons up to the paraffin, of carbon monoxide, of 

 coal, etc., offer no special interest in their equations. The 



