174 MINERALIZATION AND SOLVENT BACTERIA 



There are also varying amounts of organic phosphorus in soil. 

 This occurs in the form of lecithin, phospho-proteins, and nucleo- 

 proteins. Little has been done to determine the action of bacteria 

 upon these compounds, but it is to be expected that they would be 

 hydrolyzed by bacteria as they are by ferments. 



Lecithin yields on hydrolysis glycerin, two molecules of fatty 

 acid, phosphoric acid, and cholin: 



+ 4H 2 O = Ci8H 3 4O 2 + CielfeCh + C 3 H 8 O 3 + 

 lecithin water oleic acid palmitic acid glycerol 



H 3 P0 4 + C 6 H 16 N02 

 phosphoric acid cholin 



The phospho-proteins yield on hydrolysis amino-acids and phos- 

 phoric acid, whereas hydrolytic cleavage produces from nucleo- 

 proteins carbohydrates, phosphoric acid, purin and pyrimidin bases, 

 with the intermediate formation of nucleins and nucleic acid, as 

 may be represented by the following scheme : 



nucleo-proteins 



Schettenhelm has shown that nearly all of the nuclein substances 

 of feces disappear as they undergo autoputrefaction. He and 

 Schroeter showed that bacteria may bring about a deep cleavage of 

 yeast nucleic acid. Plenge showed that some bacteria have the 

 power to liquefy the sodium salt of nucleic acid from thymus. 



It seems reasonable, therefore, to believe that phosphorus would 

 be liberated by soil bacteria in a somewhat similar manner. It is 

 known that the bacterial flora of the soil play a highly important 

 role in rendering the phosphorus of the inorganic phosphates avail- 

 able to the higher plant. 



Brown found that twelve out of twenty-three bacteria isolated 

 from soil exerted a definite solvent action on difficultly soluble 

 plant-food. One organism which produced no gas but a large 

 amount of acid showed the greatest solvent action upon calcium 

 carbonate, whereas other organisms which produced gas largely 

 carbon dioxid but not as much acid as the former, gave an action 

 more marked than that of the stronger acid-producer upon the 

 dicalcium and tricalcium phosphates. B. subtilis, B. mycoides, 

 B. proteus mdgaris, and B. coli communis, as well as several agar 

 cultures from garden soil, were found to be capable of dissolving 



