92 



BACTERIAL METABOLISM PRODUCTS 



acid. If uric acid is given to man the greater portion of it is prob- 

 ably destroyed by bacteria in the alimentary tract, but the liver or 

 kidneys of some animals secrete a uric acid-destroying enzyme or 

 uricolytic enzyme, called uricase. It is presumably through the 

 formation of such an enzyme that bacteria are able to decompose 

 uric acid. 



Hippuric acid is hydrolyzed by certain bacteria with the forma- 

 tion of benzoic acid and glycocoll. 



o 



II 

 C C NH CHr- COOH 



/ \ 

 HC CH 



HC CH 



\ / 



C 



H 



Hippuric acid. 



COOH 





HO 



H 2 O 



CH 



|| 

 CH 



HC 



\ / 



C 

 H 



Benzoic acid 



Glycocoll 



The glycocoll may then be deaminized with the formation of 

 ammonia and acetic acid. Many extremely complex transforma- 

 tions of organic substances occur in the soil, due to bacterial 

 activity. In this medium many of the changes considered above 

 occur. These have been summarized diagrammatically for the 

 carbohydrates, proteins, oils, and waxes by Russell. 



Proteins. 



Carbohydrates ; 

 cellulose. 



-- > Oils. 



Waxes. 



I 



Undecom- 

 posed. 



CaCO, 



Products from mineral compounds may be either oxidized or 

 reduced by bacteria. Some of the important oxidations are the 

 oxidation of ammonia to nitrites, and these in turn to nitrates. 



NH 3 + 3O = HNO 2 + H 2 O 

 HNO 2 + O = HNO 3 



These changes are of especial interest to the student of soils and 

 are brought about by the nitrosomonas and nitromonas, respectively. 



Ferrous salts may be oxidized to ferric, while sulfur may be 

 oxidized to sulphuric acid. 



3O 



H 2 O H 2 SO 4 



The important reduction reactions are the ones which occur in 

 denitrification wherein the nitrate is changed to nitrite. 



Ca(NO 3 ) 2 = Ca(N0 2 )2 



O 2 



