266 DIFCO MANUAL 



ried on until all the nitrogen in the casein is converted to amino acids or other 

 compounds of relative chemical simplicity. Bacto-Casamino Acids is prepared 

 according to the method described by Mueller and Miller^ and Mueller and 

 Johnson.^ This product has a satisfactory sodium chloride content for diphtheria 

 toxin production^ '^ and has had all but the last traces of iron removed. Bacto- 

 Casamino Acids is also particularly well suited for nutritional studies, micro- 

 biological assays, the preparation of so called "synthetic" or chemically defined 

 media and media used for sulfonamide inhibitor studies. 



Mueller^ prepared diphtheria toxin in a medium containing a casein hydroly- 

 sate as the source of nitrogen. It was shown that the high sodium chloride content 

 was the limiting factor in the amount of toxin that could be produced in this 

 medium. Mueller and Miller^ described a method of reducing the sodium chloride 

 content of the hydrolyzed casein and also for reducing the iron content to a 

 minimum. Using this hydrolyzed casein supplemented with inorganic salts, 

 growth accessory factors, cystine, maltose and an optimum amount of iron, 100 

 flocculating units per ml. of diphtheria toxin were prepared. Bacto-Casamino 

 Acids duplicates this especially treated hydrolyzed casein. Complete detailed 

 directions for the preparation of diphtheria toxin are given by these authors. ^ 



Using this hydrolyzed casein, Bacto-Casamino Acids, Mueller and Miller* 

 determined the growth requirements for Clostridium tetani. Morton and Gon- 

 zalez^ employed Bacto-Casamino Acids in the medium used to study the site 

 of formation of diphtheria toxin. They obtained diphtheria toxin of high potency 

 using the method described by Mueller and Miller.^ 



Bacto-Casamino Acids has also been used in media for the testing of disin- 

 fectants. Wolf^ used Bacto-Casamino Acids or Bacto-Casamino Acids, Technical 

 in the preparation of his disinfectant test medium. Klarman and Wright^ used 

 Bacto-Casamino Acids in the semi-synthetic medium for testing disinfectants 

 described by them. Logan, Tytell, Danielson and Griner^ employed Bacto- 

 Casamino Acids in the preparation of the medium used for maintaining stock 

 cultures for the elaboration of Clostridium perfringens alpha toxin. Straus, 

 Dingle and Finland^ employed a medium containing Bacto-Casamino Acids 

 in their study of the mechanism of sulfonamide bacteriostasis. 



Bacto-Casamino Acids also is well suited for use in media for microbiological 

 assay. A description of these media with references is given on page 216 to 230. 

 Bird, Bressler, Brown, Campbell and Emmett^^ employed Bacto-Casamino Acids 

 in the medium for the assay for folic acid using Lactobacillus casei as the test 

 organism. This casein hydrolysate has been used with excellent results in media 

 for the cultivation of Hemophilus pertussis according to the method described 

 by Hornibrook^^ and by Verwey, Thiele and Sage.^- 



The following is an approximate analysis of Bacto-Casamino Acids: 



Total Nitrogen 10 per cent 



Sodium Chloride 14 per cent 



Ash 20 per cent 



P as P04 2 per cent 



Iron, 3 grams Bacto-Casamino 



Acids 15 micrograms 



^ J. Immunol., 40:21:1941. ' Soap and Sanitary Chemicals, 21:113:1945. 



3 J. Immunol., 40:33:1941. ^ J. Immunol., 51:317:1945. 



3 J. Immunol., 37:io3:i939- "J- Immunol., 42:331:1941. 



* J. Bact., 43:763:1942. ^0 J. Biol. Chem., 159:631:1945. 



J. Immunol., 45:63:1942. " Public Health Reports, 54:1847:1939. 



« J. Bact., 49:463:1945- "J- Bact., 54:71:1947. 



