490 



PRINCIPLES OF SOIL MICROBIOLOGY 



tilis, Bad. prodigiosum, Bac. putrificus, Bad. fiuorescens liquefaciens, 

 are capable of breaking down proteins with the formation of various 

 end products, one of which was ammonia. Proteins of both plant 

 and animal origin were found to be decomposed by a number of bacteria 

 giving a great variety of products. 52 



The investigations of Mlintz and Coudon and Marchal 53 called 

 attention to the existence of large numbers of bacteria and fungi in 

 the soil, capable of decomposing proteins with the formation of am- 

 monia. A solution containing 1.5 per cent nitrogen, in the form of egg 

 albumin made insoluble by means of 0.01 per cent ferric sulfate, was 

 inoculated with various bacteria; ammonia was determined after 20 

 days' incubation at 30° by distilling with MgO. 



TABLE 42 

 Protein nitrogen transformed into ammonia 



Bac. mycoides 



Proteus vulgaris 



Bac. m,esentericus vulgatus 



Sarcina lutea 



Bac. subtilis 



Bac. janthinus 



Bad. fiuorescens pulidum. 



PER 



CENT 



46 

 36 

 36 

 27 

 23 

 23 

 22 



Bac. arborescens 



Bad. fiuorescens liquefaciens 



C ephalothecium roseum 



Asp. terricola 



Botryotrichum piluliferum. . . 



Stemphylium 



Actinomyces 



PER 

 CENT 



19 

 16 

 37 

 32 

 24 

 5 

 21 



The various strains of Bac. mycoides derived from different sources 

 varied in their power to produce ammonia from proteins. In the 

 case of one strain of Bac. mycoides, Marchal obtained a transformation 

 of 58 per cent of egg-albumin nitrogen into ammonia, accompanied 

 by a marked change of the reaction of the medium to alkaline. The 

 more dilute the solution of the protein the greater was the transforma- 

 tion. Of the individual amino acids, 66 per cent of the nitrogen of 

 tyrosine in a 0.4 per cent solution, in the presence of some sugar and salts, 

 was transformed into ammonia, with 40 per cent of the leucine and 37 per 

 cent of asparagine in a 1 per cent solution. Only 9 per cent of the crea- 

 tine was transformed into ammonia. In addition to C0 2 and ammonia, 

 peptone, leucine, tyrosine, some formic, propionic and butyric acids 

 were demonstrated among the products of the digestion of albumin by 



62 Olig. Die Zersetzung pflanzlicher Futter und Nahrungsmittel durch Bak- 

 terien. Diss. Miinster (Berlin. Springer). 1903. 



"Miintz and Coudon, 1890-1893 (p. 267); Marchal, 1893 (p. 267). 



