516 



CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



phenol red, or adjust to a +1.0 

 to phenolphthalein if the reaction 

 is not between +0.5 and +1.0. 

 (h) Cohen (1922). 



(1) Dissolve 10.0 g. Difco peptone, 

 30 g. Liebig's beef extract and 

 20.0 g. of shredded agar in 

 1000.0 cc. of water. 



(2) Adjust to pH = 7.0. 



(3) Method of sterilization not spec- 

 ified. 



(i) Committee A. P. H. A. (1923). Same 

 as for 1917 (see variant (c) above, 

 but adjust the reaction to a pH 

 = 6.2 to 7.0. 



(j) Park, Williams and Krumwiede 

 (1924). 



(1) Soak 15.0 g. of agar (12.0 g. if dried 

 in the oven at 105 °C. for 30 

 minutes) in water and wash. 



(2) Dissolve 3.0 g. beef extract (Lie- 

 big's or equivalent) 5.0 g. Peptone 

 (Armour, Difco, Fairchild's or 

 equivalent) and (1) in 1000.0 cc. 

 water. 



(3) Adjust the reaction to between 

 +0.5 and +1.0 (phenolphthalein) 

 or about pH 6.6 to 7.4, if necessary. 



(4) Tube. 



(5) Sterilize at 15 pounds for 15 

 minutes. 



(6) Cool rapidly. 



(k) Park, Williams and Krumwiede 

 (1924). 



(1) Dissolve 0.3% (3.0 g.) beef ex- 

 tract and 0.5% (5.0 g.) peptone in 

 400.0 cc. distilled water by boiling 

 on the stove. 



(2) Adjust the reaction to between 

 +0.5 and +1.0 (phenolphthalein) 

 or about pH 6.6 to 7.4, if necessary. 



(3) Filter thru paper or paper pulp. 



(4) Soak 1.5% market agar (1.2% if 

 oven dried) in water, and wash 

 under tap in a sieve. 



(5) Add to (4) 600.0 cc. of distilled 

 water minus the water absorbed 

 during the washing. Weigh. 



(6) Mix (5) and (3). 



(7) Heat on the stove until the agar is 

 completely melted, stirring con- 

 stantly. 



(8) Boil and stir constantly for 

 20 minutes. 



(9) Make up the loss in weight by the 

 addition of hot distilled water. 



(10) Readjust the reaction if necessary. 



(11) Filter thru cotton or paper pulp in 

 a Buchner funnel, or run thru a 

 Sharpies centrifuge until clear. 



(12) Tube. 



(13) Sterilize in the autoclave for 

 20 minutes after the pressure 

 reaches 15 pounds, or in streaming 

 steam on 3 successive days for 

 20 minutes, after the agar is com- 

 pletely melted. 



(1) Committee A. P. H. A. (1925). 



(1) Add 3.0 g. beef extract, 5.0 g. pep- 

 tone and 15.0 g. agar (undried 

 market product as stored in the 

 ordinary laboratory cupboard) to 

 1000.0 cc. distilled water. 



(2) Boil until all the agar is dissolved. 



(3) Cool to 45°C. in a cold water bath, 

 then warm to 65 °C. in the same 

 bath without stirring. 



(4) Make up the lost weight with hot 

 distilled water and adjust the 

 reaction so that the pH value, 

 after final sterilization, will be 

 between 6.2 and 7.0. 



(5) Bring to a boiling temperature, 

 stirring frequently, restore the 

 lost weight with hot distilled water 

 and clarify. 



(6) Distribute in the desired con- 

 tainers. 



(7) Sterilize in the autoclave at 

 15 pounds (120°C.) for 15 minutes 

 after the pressure has reached 

 15 pounds. 



References: Heinemann (1905 p. 11), Com- 

 mittee A. P. H. A. (1916 p. 1316), Noyes 

 (1916 p. 93), Committee A. P. H. A. (1917 

 p. 96), Committee S. A. B. (1918 p. 115), 

 Tanner (1918 p. 48), Ball (1919 p. 77), 

 Dawson (1919 p. 142), Committee 

 A. P. H. A. (1920 p. 96), Levine (1921 

 p. 108), Cohen (1922 p. 189), Committee 

 A. P. H. A. (1923 p. 4), Committee S. A. B. 

 (1923 p. 9), Park, Williams and Krum- 

 wiede (1924 pp. 131, 132), Committee 

 A. P. H.A. (1925 p. 98). 



1696. Glaessner's Nahrstoff Heyden Extract 

 Agar 



Constituents : 

 1. Water 1000.0 cc. 



