CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



663 



that sheep serum medium gave no growth. 

 Remaining media gave good or excellent 

 growth. 

 Variants: The author added various 

 amounts of the following blood cell infu- 

 sion to the medium prepared as given 

 aVjove : 



(1) Add 2.0 cc. of red blood cells (obtained 

 by centrifuging defibrinated blood 

 (rabbit) and removing the serum) to 

 10.0 cc. of normal NaCl solution. 



(2) Keep the temperature at 100°C. for 

 3 minutes. 



(3) Shake the tubes and allow to cool. 



(4) Centrifuge and obtain the super- 

 natant fluid. 



Reference; Teague and Deibert (1922 

 p. 70). 



2059. Kulp and Rettger's Trypsinized 

 Casein Agar 



Constituents: 



1. Water 2000.0 cc. 



2. NajCOa (1.0%) 20.0 g. 



3. Casein 200.0 g. 



4. Trypsin (Fairchild's) 3.0 g. 



5. Galactose (1.0%) 20.0 g. 



6. Meat extract 6.0 g. 



7. Agar to solidify 



Preparation : 



(1) Prepare a 1.0% solution of NaaCOs 

 and heat to boiling. 



(2) Add 20.0 g. of granulated casein to 

 2 liters of boiling (1). Add the 

 casein in small quantities at a time, 

 and stir after each addition until 

 complete solution has taken place. 



(3) Cool to about 40°C. 



(4) Add 10 or 12.0 cc. water containing 

 3.0 g. of fresh Fairchild's trypsin. 



(5) Mix well and add 25.0 cc. chloroform. 



(6) Flask and incubate at 37°C. for 

 48 hours. 



(7) Neutralize to litmus by the addition 

 of HCl. 



(8) Heat in a double boiler to remove 

 the chloroform. 



(9) Filter. If chemically pure casein is 

 used the filtrate will be clear and 

 have a bright amber color. Com- 

 mercial casein makes a darker 

 colored product due to the small 

 lactose content. 



(10) Distribute in quantities equal to 

 10.0 g. of the original casein into 

 flasks. 



(11) When ready for use add water to 

 make 1000.0 cc. to each sterile flask 

 and dissolve 3.0 g. commercial meat 

 extract, agar to give the desired 

 consistency, and 1.0% galactose in 

 each flask. 



Sterilization: Sterilize (10) in the auto- 

 clave. Final sterilization not specified. 



Use: Cultivation of Lactobacillus acid- 

 ophilus and Lactobacillus bulgaricus. 

 The authors reported that any other 

 carbohydrate might be used instead of 

 galactose, but galactose favored the 

 growth of the organisms most. This me- 

 dium is slightly inferior to a medium 

 prepared from klim powdered skim milk. 

 See the following medium. 



Variants: Any other carbohydrate may be 

 used instead of galactose. 



Reference: Kulp and Rettger (1924 p. 363). 



2060. Kulp and Rettger's Trypsinized 

 Klim Agar 



Constituents: 



1. Water 2000.0 cc. 



2. NaoCOj (1.0%) 20.0 g. 



3. Klim (powdered skim milk) 200.0 g. 



4. Meat extract 3.0 g. 



5. Trypsin (Fairchild's) 3.0 g. 



6. Galactose (0.5%) 10.0 g. 



7. Agar to solidify 

 Preparation : 



(1) Prepare a 1.0% solution of Na2C03. 



(2) Add 200.0 g. of klim (powdered skim 

 milk) to 2000.0 cc. of cold (1). Add 

 the klim in small quantities and stir 

 after each addition, until solution 

 is complete. 



(3) Heat to about 40°C. 



(4) Add 10.0 to 12.0 cc. of water contain- 

 ing 3.0 g. of fresh Fairchild's trypsin. 



(5) Mix thoroly and add 25.0 cc. chloro- 

 form. 



(6) Flask and incubate at 37°C. for 

 48 hours. 



(7) Add HCl to neutralize to litmus. 



(8) Hea: in a double boiler to remove the 

 chloroform. 



(9) Distribute into 100.0 cc. lots. 



(10) When ready for use add water to 

 each sterile flask to make 1000.0 cc, 



