FERMENTATION REACTION 279 



(C) Invertase. (Convert saccharose into a mixture of 

 dextrose and laevulose e.g., B. fluorescens liquefaciens.) 



Medium Required: 



Inosite-free bouillon. 

 Reagents Required: 



Cane sugar, 2 per cent, aqueous solution. 



Carbolic acid. 



METHOD. 



1. Prepare tube cultivations and incubate. 



2. Add 2 per cent, of carbolic acid to the sugar 

 solution. 



3. Mix equal quantities of the carbolised sugar solu- 

 tion and the cultivation in a test-tube; allow the 

 mixture to stand for several hours. 



4. Filter. 



Test the filtrate for reducing sugar as in the pre- 

 ceding section. 



(D) Rennin and "Lab" Enzymes. (Coagulate milk 

 independently of the action of acids; e. g., B. pro- 

 digiosus.) 



Media Required: 



Inosite-free bouillon. 

 Litmus milk. 



METHOD. 



1. Prepare tube cultivations and incubate. 



2. After incubation heat the cultivation to 55 C. 

 for half an hour, to sterilise. 



3. By means of a sterile pipette run 5 c.c. of the 

 cultivation into each of three tubes of litmus milk. 



4. Place in the cold incubator at 22 C. and examine 

 each day for ten days. 



Absence of coagulation at the end of that period 

 will indicate absence of rennin ferment formation. 



Fermentation Reactions. 



As tested upon carbohydrate substances and organic 

 salts. 



