CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



561 



Variants : 



(a) Smith specified that the reaction of 

 the agar be slightly alkaline (0.5%). 



(b) Smith (1905) also gave the following 

 method of preparation: 



(1) Add 10.0 g. of c.p. lactose to 1000.0 

 cc. of sugar-free meat infusion 

 agar. 



(2) Add 20.0 cc. of a saturated watery 

 solution of lime-free blue litmus 

 to (1). 



(3) Sterilization not specified. 



(c) Heinemann prepared a similar me- 

 dium as follows: 



(1) Add 1.0% lactose to sugar-free 

 infusion agar. 



(2) Tube in 8.0 cc. quantities. 



(3) Add 1.0 cc. of 1.0% sterile litmus 

 solution to each tube before using. 



(d) Committee A. P. H. A. (1913). 



(1) Boil 10.0 or 15.0 g. of thread agar 

 in 500.0 cc. of water for half an 

 hour and make up weight to 500.0 

 g. or digest for 15 minutes in the 

 autoclave. Cool to 60°C. 



(2) Infuse 500.0 g. of lean meat for 24 

 hours with 500.0 cc. distilled water 

 in a refrigerator. 



(3) Make up lost weight. 



(4) Strain thru cotton flannel. 



(5) Weigh. 



(6) Add 2.0% Witte's peptone and 

 warm on the water bath until 

 solution is complete. Do not heat 

 above 60 °C. 



(7) Mix 500.0 cc. (6) and 500.0 cc. of 

 (1), keeping the temperature below 

 60 "C. 



(8) Titrate and adjust the reaction to 

 neutral to phenolphthalein, add- 

 ing normal HCl or NaOH. 



(9) Heat on a water bath for 40 

 minutes. 



(10) Make up lost weight. 



(11) Readjust to neutrality if neces- 

 sary and boil 5 minutes. 



(12) Restore lost weight. 



(13) Filter thru absorbent cotton and 

 cotton flannel. 



(14) Titrate and record final reaction. 



(15) Add 1.0% lactose and sufficient 

 azolitmin solution. 



(16) Tube in 10.0 cc. quantities. 



(17) Sterilize for 15 minutes in the 

 autoclave at 120°C., or for 30 

 minutes on each of 3 successive 

 days. 



(e) Ball (1919) prepared a similar medium 

 as follows: 



(1) Add 1.0% lactose to nutrient agar 

 just before sterilization. 



(2) Reaction of (1) to be neutral. 



(3) Boil 1.0% Kahlbaum's azolitmin 

 for 5 minutes. 



(4) Add (3) to the tubes just before 

 sterilization, or if to be used in 

 plates, add at the time of plating. 



(f) Abbott (1921) gave the following 

 method of preparation: 



(1) Prepare a nutrient agar so that the 

 alkalinity is such that it requires 

 0.1 cc. of a 1:20 normal H2SO4 

 solution to neutralize 1.0 cc. of 

 medium. Indicator not specified. 



(2) Add 2.0 to 3.0% lactose. 



(3) Decant into test tubes. 



(4) Sterilize in the usual way (method 

 not given) . 



(5) Add sufficient sterile litmus tinc- 

 ture to each tube to give a decided 

 but not intense blue color. Add 

 the litmus under aseptic con- 

 ditions. 



(g) Giltner gave the following methods 

 of preparation. The media were 

 used in water analysis. 



(1) (1) Prepare infusion agar using 



equal parts meat infusion and 

 water, with 1.0% peptone and 

 1.5% agar. 



(2) Adjust the reaction to -f 1.0. 



(3) Add 1.0% lactose and 2.0% 

 azolitmin solution just before 

 tubing. 



(4) Tube. 



(5) Sterilize for 30 minutes on 

 3 successive days. 



(2) (1) Preparation of meat infusion 



not given. 



(2) Strain (1) thru a piece of clean 

 cheese cloth. 



(3) Place 2.0% washed agar in 

 500.0 cc. distilled water. 



(4) Weigh (3). 



(5) Digest over a free flame. 



(6) Add distilled water to make up 

 the loss in weight. 



