[HARRISON .t VANPERLECK] .ESCULIN BILE SALT MEDIA 1S9 



carbohydrates are present in abundance no enzyme is needed, and 

 experience has shown that no aesculetin is formed in the presence 

 of carbohydrates. 



The following media were made as follows: 



Distilled water, 1.5% agar, 0.5% peptone, 0.25% bile salt, iron 

 0.1%, sesculin 0.1%,- 



Final Acidity 0.6 = no Liebig's extract — very good plates 

 " 0.05% " 



colonies brown in colour 

 « " " 0.10% " extract — crowded plates with 



light brown colonies. 

 " " " 0.15% " extract — crowded plates with 



light brown colonies. 

 " '* " 0.20% " extract— crowded plates with 



light brown colonies. 

 « " " 0.25% " extract — crowded plates with 



no coloured colonies. 

 " " " 0.30%, " extract— crowded plates with 



no coloured colonies. 



These results show clearly that Liebig's meat extract had an 

 injurious influence on the medium. 



There exists some doubt concerning the identity of the enzyme 

 which acts on the glucoside aescuHn. The general beUef is that 

 it is the enzyme "emulsin" which causes the reaction. (3) There is, 

 however, cause to doubt this statement. Emulsin obtained from 

 bitter almonds (Amygdalus communis) splits among other enzymes 

 salicin. B. coli, however, is unable to spHt saUcin, as we tried to 

 replace sesculin by salicin, but without result. Therefore, we are 

 bound to conclude that the enzyme of B. coli and />'. aerogenes cannot 

 be Emulsin. 



jEsculetiii in Liquid Media. 



We have repeatedly tried sesculin in liquid media for the purpose 

 of isolating B. coli from large samples of water. Two different lots 

 were made up. 



A. In 1000 cc. distilled water we dissolved by boiling 

 20 grams peptone Witte 

 0.5 grams sesculin 

 0.5 " iron citrate scales 



