CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



511 



Variants: Meier studied the bacterial 

 counts of milk and whey, using the fol- 

 lowing medium: 



(1) Dissolve 15.0 g. of agar, 10.0 g. 

 Liebig's meat extract, 10.0 g. Witte's 

 peptone, 5.0 g. NaCl and 2.0% gly- 

 cerol, 2.0% glucose or 4.5% lactose in 

 1000.0 cc. water. 



(2) Neutralize to litmus and then add 

 10.0 cc. N/1 soda solution per liter 

 medium, 



(3) Sterilization not specified. 

 References: Banning (1902 p. 395 and 426), 



Meier (1918 p. 438). 



1694. Helm's Meat Extract Salt Agar 



Constituents : 



1. Water 1000.0 cc. 



2. Agar 12.5 g. 



3. Meat extract 10.0 g. 



4. Peptone 10.0 g. 



5. NaCl 5.0 g. 



Preparation : 



(1) Dissolve 2, 3, 4 and 5 in 1. 



(2) Neutralize with NaOH to litmus. 



(3) Filter and distribute into culture 

 plates containing different amounts of 

 NaOH solution so that the final 

 volume be 10.0 cc. 0.5% alkaline 

 gave the best results. 



Sterilization: Sterilize in steam (exact 

 method not given) and allow plates to 

 dry for 1 day with the cover removed. 



Use : General culture medium. Heim used 

 the medium to study effect of alkalinity 

 and acidity on growth of anthrax bacillus. 



Variants: The following authors prepared 

 the medium as indicated: 

 (a) Ravenel (1899). 



(1) Add 10.0 g. peptone, 5.0 g. NaCl 

 and 5.0 g. Liebig's beef extract to 

 500.0 cc. water. 



(2) Boil (1) for 3 minutes and neutral- 

 ize (indicator not specified). 



(3) Chop 12.0 g. agar into small pieces 

 and add to 500.0 cc. of water. 



(4) Place in the autoclave and run the 

 pressure to two atmospheres 

 (135.1°C.). Turn out the flame. 



(5) Allow the autoclave to cool to 

 100°C. before opening. 



(6) Cool (2) and (5) to 60°C. and mix. 



(7) Beat the whites of two eggs in 

 50.0 cc. water and add to (6). 



(Blood serum may be used instead 

 of egg white.) 



(8) Boil for 3 to 5 minutes and filter 

 thru paper. 



(9) Sterilization not specified. 



(b) Frost (1903). 



(1) Add 15,0 g. agar to 500.0 cc. of 

 water and dissolve by heating to 

 120°C. in the autoclave, shutting 

 off the gas and allowing to cool, 

 or boil until the agar is dissolved 

 (about 30 minutes) and make up 

 the loss of water due to evapo- 

 ration. 



(2) Weigh out 3.0 g. of beef extract 

 such as Liebig's and add 500.0 cc. 

 of water. 



(3) Add 10.0 g. peptone and 5.0 g. NaCl 

 to (2). 



(4) Heat until solution is complete. 



(5) Neutralize to phenolphthalein. 



(6) Cool to 60° and add one egg. 



(7) Add (6) to (1). 



(8) Boil until albumin is coagulated 

 and floats in the clear liquid and 

 restore the weight. 



(9) Readjust the reaction if necessary. 



(10) Add 0.5% normal HCl. 



(11) Filter thru cotton supported in a 

 coil of wire using a suction pump. 



(12) Tube. 



(13) Sterilize in steam for 15 minutes 

 on 3 successive days or in the auto- 

 clave for 20 minutes at 120°C. 

 Slant some of the tubes after final 

 sterilization. 



(c) Hesse (1908), 



(1) Dissolve 10.0 g. Witte's peptone, 

 5.0 g. Liebig's meat extract and 8.5 

 g. NaCl in 500.0 cc. distilled water 

 by boiling. 



(2) Dissolve 5.0 g. agar in 500.0 cc. dis- 

 tilled water and boil. 



(3) Filter (1) thru a filtering apparatus 

 and (2) thru paper. 



(4) Mix the two filtrates. 



(5) Make up to 1 liter and boil again. 



(6) Distribute in 10.0 cc. lots in tubes. 



(7) Do not add alkali. 



(8) Sterilize in the autoclave under 

 2 atmospheres pressure for 20 

 minutes. 



(d) Hesse (1908). 



(1) Dissolve 8.5 g. NaCl, 5.0 g. Liebig's 



