112 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



thirty minutes (disagreeing with Fermi). Schmailowitsch 1 

 states that some bacteria produce an enzyme acting in acid 

 medium upon gelatin but not upon albumin, and this enzyme 

 carries the digestion only as far as the gelatin-peptone stage, 

 whereas the enzymes acting in an alkaline medium carry the 

 splitting through to leucin, tyrosin, etc. Plenge 2 suggests that 

 there is a special enzyme digesting nucleoproteids. The bac- 

 terial amylolytic enzyme acts like ptyalin. 



Cacace 3 investigated the splitting products of gelatin and 

 coagulated blood when digested by B. anthracis, Staph. pyogenes 

 aureus, and Sarcina aurantiaca, and found that proteoses and 

 peptone are produced, which disappear in the later stages of 

 digestion. Rettger 4 found leucin, tyrosin, tryptophan, as well 

 as phenols, skatol, indol, aromatic oxy-acids, and mercaptan, 

 among the products of bacterial decomposition of egg-albumen 

 and meat ; proteoses and peptones appear in the early stages, 

 but later disappear, as also eventually do the leuciu, tyrosin, etc. 

 Cholin has also been found in the products of atitolysis. 5 Mav- 

 rojannis 6 found that some bacteria digest gelatin only as far as 

 the gelatose stage (which is determined by its being hardened 

 by formalin), while others carry the digestion to peptones and 

 non-proteid substances which cannot be hardened by formalin. 



The digestive power of the nitrates of cultures and of killed 

 bacteria is far less than that of the living bacteria (Knapp 7 ). 

 Streptococci digest proteids of exudates feebly, staphylococci 

 more rapidly, and colon bacilli are still more active. He could 

 find no relation between the proteolytic power of the bacteria 

 and the severity of the infection from which they came. 



Immunity against bacterial enzymes may be secured as 

 it is against other enzymes. Abbott and Gildersleeve 8 found 

 that by injections into animals of proteolytic bacterial nitrates 

 which were only slightly toxic, the serum of the animals 

 acquired a slight but specific increase in resistance to the proteo- 

 lytic enzymes of the filtrates. Normal serum contains a cer- 

 tain amount of enzyme-resisting substance. Other observers 

 have found that immunization against living or dead bacteria 

 leads to the production of substances antagonistic to their 



1 Abst. in Biochem. Centr., 1903 (1), 230 ; see also DeWaele, Cent. f. Bakt, 

 1905 (39), 353. 



2 Zeit. f. physiol. Chem., 1903 (39), 190. 



3 Cent. f. Bakt., 1901 (30), 244. 



4 Amer. Jour, of Physiol., 1903 (8), 284. 



6 Kutscher and Lohmann, Zeit. physiol. Chem., 1903 (39), 313. 



6 Zeit. Hygien. u. Infektionskr. , 1903 (45), 108. 



7 Zeit. f.Heilk. (Chir. Abt.) 1902 (23), 236. 



8 Loc. tit. 



