DEHYDRATED CULTURE MEDIA 235 



BAGTO-ARGININE ASSAY MEDIUM (B466) 

 BAGTO-GYSTINE ASSAY MEDIUM (B467) 

 BAGTO-TYROSINE ASSAY MEDIUM (B468) 

 BAGTO-PHENYLALANINE ASSAY MEDIUM (B469) 



These media have been just recently developed for the microbiological assay of 

 Arginine, Cystine, Tyrosine and Phenylalanine. They are similar in composition 

 to the media described immediately above, being free of the amino acid 

 specified for assay, but containing all other growth factors and nutriments 

 necessary for the growth of Leuconostoc mesenteroides P-60 ATCC 8042. The 

 addition of the amino acid under assay in specified increasing concentrations 

 gives a growth response by L. mesenteroides which may be measured acidimetri- 

 cally or turbidimetrically. Complete directions for the assay is given on the 

 package label. 



To rehydrate these media, dissolve 105 grams in 1000 ml. distilled water and 

 heat to boiling for 2-3 minutes. The slight precipitate which forms should be 

 evenly distributed by shaking. Five (5) ml. of the medium are added to each 

 tube in the preparation of the tubes for the standard curve and to each tube con- 

 taining material under assay. For the final assay each tube must contain 5 ml. 

 of rehydrated medium, increasing amounts of the standard or the unknown and 

 sufficient distilled water to give a total volume of 10 ml. per tube. The tubes are 

 autoclaved for 10 minutes at 15 pounds pressure (121°C.). Oversterilization of 

 the medium will give unsatisfactory results. 



One hundred grams of each of these media will make 1 .9 liters of final medium. 



BACTO 



TRYPTOPHANE ASSAY MEDIUM (B327) 



DEHYDRATED 



Bacto- Vitamin Free Riboflavin 0.0004 g, 



/^-Aminobenzoic Acid, Difco . 0.0002 g 



Niacin 0.0002 g 



Biotin 0.0000008 g 



Dipotassium Phosphate 1 g 



Monopotassium Phosphate 1 g 



Magnesium Sulfate 0.4 g, 



Sodium Chloride 0.02 g 



Ferrous Sulfate 0.02 g 



Manganese Sulfate 0.02 g 



Casamino Acids 12 



Bacto-Dextrose 40 g, 



Sodium Acetate 20 g 



/-Cystine, Difco 0.2 g 



Adenine Sulfate 0.02 g 



Guanine Hydrochloride 0.02 g. 



Uracil 0.02 g, 



Thiamine Hydrochloride . . . 0.0002 g. 



Calcium Pantothenate .... 0.0002 g, 



Pyridoxine Hydrochloride . . 0.0004 g 



Bacto-Tryptophane Assay Medium is a complete dehydrated medium for the 

 assay of /-tryptophane or c?/-tryptophane. It is free from tryptophane but contains 

 all the other factors necessary for the growth of Lactobacillus arabinosus 17-5 

 ATCC 8014. The addition of tryptophane in certain concentrations gives a linear 

 growth response by L. arabinosus 17-5, which may be measured acidimetrically. 

 Bacto-Tryptophane Assay Medium is prepared according to the formula de- 

 scribed by Greene and Black.^ 



The following procedure is recommended for the assay of tryptophane using 

 the dehydrated medium: 



Stock cultures of L. arabinosus 17-5 are prepared by stab inoculation of Bacto- 

 Micro Assay Culture Agar. Following incubation at 35-3 7 °C. for 24^8 hours, 

 the tubes are stored in the refrigerator. Transplants are made at monthly inter- 



