118 CHEMISTRY OF BACTERIA A\D THEIR PRODUCTS 



Kaiitorowicz ""'' and de AVaele ''•' state tliat bacteria contain an in- 

 tracellular anti-protease wiiicli, with most bacteria, holds in check 

 the proteolytic action; only with tlie liquefying bacteria are the 

 proteases in excess. Bacteria grow well in strong solutions of en- 

 zymes, and without destroying the enzymes (Fermi).®" After Gram- 

 negative bacteria have been heatetl to 80° they are readily digested by 

 trypsin, pepsin or leucocytic proteases; but Gram-positive bacteria 

 are resistant even after heating. This is ascribed by Jobling and 

 Petersen""'' to the unsaturated fatty acids, wliicli are present in 

 greater amounts in Gram-positive bacteria. 



Autolysis of Bacteria. — Autolysis occurs also in bacteria, their 

 proteolytic enzymes digesting the cell substance whenever the organ- 

 isms are killed by agents (chloroform, toluene, etc.) that do not de- 

 stroy these enzymes, and which, being fat solvents, may facilitate di- 

 gestion by removing the inhibitory lipoids. Even the absence of food 

 leads to autolysis, presumably because the normally existing auto- 

 lytic processes are not counteracted by synthesis of new protein ma- 

 terial ; hence, autolysis occurs M^hen bacteria are placed in salt solution 

 or distilled water. Although it had been known for many years that 

 yeast cells digest one another when there is nothing else for them to 

 live upon, the first definite study of bacterial autolysis seems to have 

 been made by Levy and PfersdorfP "^ and Conradi.^- The former 

 digested anthrax bacilli (in whose bodies are contained rennin, lipase 

 and protease) under toluene for several weeks and obtained a slightly 

 toxic product. Conradi permitted dysentery bacilli and typhoid 

 bacilli to digest themselves in normal salt solution for twenty-four to 

 forty-eight hours at 37° C, and obtained in this way the soluble, 

 highly poisonous endotoxins of the bacteria, which are liberated by 

 the destruction of the bacterial structure by the autolytic enzymes. 

 Longer autolysis results in the destruction by the enzymes of the en- 

 dotoxins themselves. Rettger '''^ found among the autolytic products 

 of bacteria, leucine, tyrosine, basic substances, and phosphoric acid. 

 Under favorable conditions complete autolysis can occur in two to 

 ten days. 



Brieger and IMayer "* found that at room temperature (15° C.) 

 practically no autolysis occurs with typhoid bacilli in distilled water, 

 and the soluble products thus obtained are quite non-toxic, although 

 if injected into animals they give rise to the production of agglu- 

 tinins and bacteriolysins. Bertarelli '''■' has used tlie products of 



ssMiinfh. mod. Woch., 1909 (.'56), 897. 

 •'•oCont. f. Bakt., 1909 (50), 40. 

 00 Arch. Farmac'ol., 1909 (S), 481. 

 «oa,Tour. Kxy). Med., 1914 (20), 321. 

 «i Dc'ut. nicd. Wocli.. 1902 (2S), 879. 

 12 Ibid., ]'M):\ (29), 2(). 

 03 Jour. :M('d. Kcsoaroli, 1904 (13), 79. 

 «4Dcut. iiK'd. WOcli., 1904 (.30), !)S0 

 05 Cent. f. Bakt., 1905 (38), 5S4. 



