268 DIFGO MANUAL 



yielding a clear colorless solution. The following is a typical analysis of Bacto- 

 Vitamin Free Casamino Acids: 



Total Nitrogen 7 per cent 



Sodium Chloride 38 per cent 



Ash 41 per cent 



* J. Biol. Chem., 171:265:1947. 



AMINO ACIDS 



A DISCUSSION of the amino acids most commonly used is given here. Additional 

 amino acids are available as required. Difco amino acids are pure and recom- 

 mended as standards for chemical and microbiological procedures as well as for 

 use in media of chemically defined composition for nutritional studies. 



BAGTO-ASPARAGINE ( B 144) 



Bacto-Asparagine is /-asparagine of exceptional purity. It is recommended as 

 a particularly useful ingredient of synthetic culture media employed in studies 

 of bacterial nutrition. 



Asparagine is used as a source of organic nitrogen of known chemical com- 

 position. It is readily available for bacterial energy and growth when used in 

 culture media. Bacto-Asparagine is widely employed in media for the mass 

 cultivation of Mycobacterium tuberculosis for use in the preparation of tuber^ 

 culin for the detection and eradication of tuberculosis. Asparagine has also 

 been used in recent investigations for the growth of tubercle bacilli as reported 

 by Dubos and Davis,^ and others, 

 ij. Exp. Med., 83:409:1946. 



J/- ALANINE, DIFGO (B182) 



Alanine has been used occasionally in culture media as a source of nitrogen 

 in studies of the metabolism of various organisms. c^/-Alanine, Difco is a highly 

 purified amino acid suitable for use in studies of this type. 



/-GYSTINE, DIFGO (B184) 



Cystine is used extensively in synthetic culture media, particularly those 

 employed in studies of bacterial metabolism. Davis and Ferry^ devised a cystine 

 medium for use in their studies on diphtheria toxin production, and DuvaP 

 employed a cystine medium for propagation of Mycobacterium leprae. Shaw^ 

 and Rhamy* used cystine media for the cultivation of Pasteurella tularensis. 

 Cystine is employed in the media specified by the National Institute of Health,^ 

 for the sterility testing of biologicals, for sterility testing as specified in the 

 Pharmacopeia^ and National Formulary''' and for the sterility testing of anti- 

 biotics according to the method of the Food and Drug Administration.^ 



/-Cystine, Difco is a highly purified amino acid recommended for use in the 

 preparation of culture media. 



1 J. Bact., 4:217:1919. Pharmacopeia of the United States, XIV Re- 



^ J. Exp. Med., 12:649:1910. vision: 758: 1950. 



Zentr. Bakt., I Abt. Orig., 118:216:1930. ' National Formulary, 9th Edition: 778: 1950. 



Am. J. Clin. 

 National Inst: 

 Media for tl 

 Feb. 5j 1946. 



* Am. J. Clin. Path., 3:121:1933. ^ Compilation of Tests and Methods of Assay for 



* National Institute of Health Circular : Culture Antibiotic Drugs, Federal Security Agency, 

 Media for the Sterility Test, 2nd Revision: Food and Drug Administration. 



