DECOMPOSITION OF PROTEINS 489 



not toxic to ammonia forming organisms. 48 No ammonia is formed 

 from cyanamide in sterile soil, but considerable amounts of ammonia 

 are produced on the addition of urease; this indicates the presence of 

 urea. The urea is, of course, decomposed in the soil by various 

 organisms. 49 



Among the other nitrogenous substances which are gradually 

 decomposed in the soil by microorganisms, we find various alkaloids, 

 such as cocaine, strychnine, morphine, etc. 80 



Chitin is found among the synthesized constituents of the cells of 

 microorganisms, especially fungi, and is constantly added to the store 

 of soil organic matter. It is a polymer of mono-acetyl-glucosamine 

 (Ci4H 26 N 2 Oio)„, giving acetic acid and glucosamine upon hydrolysis. 

 It gives a violet color with chlor-zinc iodide and a brown-red color 

 with a solution of iodine and potassium iodide. Certain bacteria and 

 actinomyces decompose chitin in the soil by means of an enzyme 

 chitinase. 51 Chitin can be used by these organisms both as a source 

 of carbon and nitrogen, in the presence of K 2 HP0 4 and MgS0 4 . 



To be able to understand, how the decomposition of proteins and 

 other nitrogenous substances by microorganisms in the soil results in 

 the formation of ammonia, how different organisms bring about differ- 

 ences in the accumulation of the ammonia and how the latter is in- 

 fluenced by the soil environmental conditions, a knowledge of the 

 action of the different organisms upon proteins, under different con- 

 ditions, is essential. 



Ammonia formation by bacteria. The earlier investigators of bacterial 

 metabolism, like Hoppe-Seyler, Bienstock, Hauser and others, found 

 that mixtures and pure cultures of bacteria, like Bad. vulgare, Bac. sub- 



48 Norris, R. V., Vismanath, B., and Aiyer, C. V. R. A preliminary note on 

 the decomposition of calcium cyanamide in South Indian soils. Mem. Dept. 

 Agr. India, Pusa., 7: 55-75. 1923; Ulpiani, C. Evoluzione chimica e biochimica 

 della calciocianamide nel terreno agrario. Gaz. Chim. Ital., 40: 613-666. 1910. 



49 Further information on ammonia formation from cyanamide is given by 

 Perotti, R. Uber den mikrobiochemischen Prozess der Ammonization im Acker- 

 boden. Centrbl. Bakt. II, 20: 514-518. 1908; tlber die Stickstoffernahrung der 

 Pflanzen durch Amidsubstanzen. Ibid., 24: 373-382. 1909; Lohnis, 1910 (p. 

 xiii), p. 590. 



50 Lavialle, P. Destruction of alkaloids in the soil. Bull. Sci. pharmacol., 

 30: 321-325. 1923; (Chem. Abstr., 17: 2732). 



81 Benecke, \V. t)ber Bacillus chitinovorus, einen Chitin zersetzenden Spalt- 

 pilz. Bot. Ztg., 63: 227-272. 1905; Folpmers, T. Die Zersetzung des Chitins 

 und des Spaltungsproduktes desselben, des Glucosamins, durch Bakterien. 

 Chem. Weekbl., 18: 249. 1921; (Centrbl. Bakt. II, 57: 97-98. 1922). 



