BACTERIAL ENZYMES 



111 



PROTEOLYTIC ENZYMES, DIGESTING 



Rennin is produced by many bacteria, as is shown by their 

 coagulating milk, independent of any acid reaction. 1 



An interesting observation made by Schmailowitsch 2 is that 

 the amount and nature of enzymes produced by bacteria is modi- 

 fied by the amount and nature of their food. When they 

 receive no food, they secrete no enzymes ; when grown on pro- 

 teid-rich media they produce much proteolytic enzyme ; grown 

 on a carbohydrate medium they produce chiefly amylolytic en- 

 zymes. This observation recalls Pawlow's demonstration of the 

 similar influence of the quality of food upon the proportion of 

 the various digestive enzymes contained in the pancreatic juice ; 

 under proteid diet the trypsin is in excess ; under starch diet the 

 amylopsin is in excess, etc. Abbott and Gildersleeve 3 have 

 corroborated this statement, finding that bacteria grown on gel- 

 atin produce much more active gelatin-dissolving enzyme than 

 do bacteria grown on bouillon. This phenomenon they would 

 explain on the basis of Welch's hypothesis that bacteria react 

 to chemical substances by producing antagonistic substances, just 

 as higher organisms do under similar conditions. It is probably 

 closely related to the difference of composition observed in bac- 

 teria grown on different media (vide supra). 



In general, bacterial proteolytic enzymes resemble trypsin 

 more closely than they do pepsin, acting best in an alkaline 

 medium ; but the enzymes extracted from bacterial cultures are 

 very feeble as compared with pancreatic trypsin. Abbott and 

 Gildersleeve found that the gelatin-dissolving enzyme of bac- 

 teria resists a temperature of 100 C. for as long as fifteen to 



1 Contradicted by DeWaele, Cent. f. Bakt., 1905 (39), 353. 



2 Wratschebnaja Gazetta, 1902, p. 52. 



3 Jour. Med. Research, 1903 (10), 42. 



