478 PRINCIPLES OF SOIL MICROBIOLOGY 



oxidation. Jeannert, 16 studying the decomposition of proteins under 

 anaerobic conditions, demonstrated among the decomposition prod- 

 ucts of gelatin, C0 2 , NH 3 , H 2 S, acetic-, butyric-, and valeric acids, 

 glycocoll and leucine. These substances, except glycocoll, were also 

 formed from albumin, in addition to hydrogen, hydrogen sulfide, 

 tyrosine and amido-valeric acid. 



These investigations were followed by numerous others with crude 

 and pure cultures of bacteria, whereby amino acids, fatty acids and 

 certain gases, including NH 3 , C0 2 and H 2 S, were demonstrated as 

 products of hydrolysis. In the case of the so-called putrefactive 

 organisms, indol, skatol, phenol, and other substances were also demon- 

 strated. Bac. subtilis was found 17 to produce from cotton-seed meal 

 in five weeks: albumoses, peptones, phenyl-acetic and phenyl-pro- 

 pionic acids, ammonia, mercaptan, basic amines, H 2 S, and C0 2 ; after 

 three months, valerianic and indol-acetic acids, indol, skatol, and 

 phenol were also demonstrated in the culture. 



The presence of specific amino acids in the protein molecule is neces- 

 sary for the formation of some of the final products. It is sufficient 

 to mention tryptophane as a source of indol, cysteine and other sulfur 

 compounds as a source of H 2 S, and tyrosine as a source of cresol and 

 phenol. 



A number of bacteria are unable to attack pure proteins; only the 

 degradation products are acted upon. The presence of simple nitro- 

 gen compounds may be required to start the development of the or- 

 ganism. 18 In many instances, however, even native proteins will be 

 acted upon after the organism starts to grow and the proper enzymes 

 are formed. Under natural conditions, the proteins are usually always 

 accompanied by small amounts of their derivatives or by simple nitro- 

 gen compounds, especially when added to the soil. 



The nature of the products formed will depend not only upon the 



16 Jeannert, J. Untersuchungen liber Zersetzung von Gelatine und Eiweiss 

 durch die geformten Pankreasfermente bei Luftausschluss. Jour, prakt. Chem. 

 N. F., 15: 353-389. 1877. 



17 Konig, J., Spieckermann, A., and Olig, A. Die Zersetzung pflanzlicher 

 Futtermittel durch Bakterien. Centrbl. Bakt. II, 10: 535-549. 1903. 



18 Bainbridge, F. A. The action of certain bacteria on proteins. Jour. Hyg., 

 11: 341-355. 1911; Sperry, J. A., and Rettger, S. F. The behavior of bacteria 

 towards purified animal and vegetable proteins. Jour. Biol. Chem., 20: 445-459. 

 1915; Berman, N., and Rettger, L. F. Bacterial nutrition: further studies on 

 the utilization of protein and non-protein nitrogen. Jour. Bact., 3: 367-388. 

 1918. 



