THE NUTKITION OF BACTEKIA 



Exercise 8. Preparation of Bouillon 



Two metliods of preparation are used by bacteriologists, but 

 method B is more convenient and hence more generally used. It 

 is open to the followiag objec- 

 tion: Liebig's Beef Extract 

 (the one commonly used) 

 often contains very resistant 

 bacterial spores. Triple steri- 

 lization at 100° C. sometimes 

 faUs to kill these organisms; 

 however, the bouOlon can 

 be sterUized by heating to 

 120°C. in the autoclave and 

 subsequently used either as pig. g. Cotton plugs 



a culture medium or as a ^, correctly made plug ; 5, shaUow plug 

 basis for making up nutrient which will be easily displaced; C, plug 



which does not protect the tube from the 

 gelatm, agar, etc. entrance of dust 



A B 



1. Place 500 g. of lean 

 chopped beef, free from fat, in 

 1000 cc. of distUled water. Stir 

 and set in a refrigerator for 

 twelve to twenty-four hours. 



2. Strain the meat water 

 through a piece of clean cheese- 

 cloth. Add distilled water to 

 make filtrate up to 1000 cc. 

 Place in. a flask or agate-ware 

 kettle for cooking. 



3. Add to either of the above 10 g. peptone and 5 g. sodium 

 chloride. Weigh the vessel containing the solution on a balance 

 and record the weight. 



4. Cook the bouillon on a steam bath or in the Arnold steril- 

 izer fifteen to twenty minutes. Add water to restore to the 

 original weight. 



1. Add 4 g. of Liebig's Beef 

 Extract to 1000 cc. of dis- 

 tUled water. 



2. Place the materials in a 

 flask or agate-ware kettle for 

 cooking. 



