38 DIFCO MANUAL 



green. The American Water Works Association made extensive studies of this 

 problem through its Committee No. 1 on "Standard Methods of Water Analysis." 

 Dunham and Schoenlein^ have recorded their investigations of the proportions 

 of bile and brilliant green giving optimum results. They reported that, under 

 the conditions of their investigations, a reduced bile content and a dilution of dye 

 higher than that originally suggested by Muer and Harris^, improved conditions 

 for the development of Escherichia coli. The necessity of maintaining the proper 

 concentration of ingredients after the water sample is added was emphasized. 

 Jordan^ indicated in his report that this medium is slightly superior to Lactose 

 Broth and to the more concentrated bile medium in the detection of the coliform 

 group in water. McCrady and Langevin'' reported that Bacto-Brilliant Green 

 Bile 2% is satisfactory for the detection of the coliform group in controlling the 

 pasteurization of milk. McCrady^ in studies on media for the detection of the 

 presence of coliform organisms in water, found that while selective media were 

 not as satisfactory as Lactose Broth for the presumptive test, they could be 

 recommended for confirmation of the presumptive test and that for this purpose 

 Brilliant Green Bile 2% was most satisfactory. 



Bacto-Brilliant Green Bile 2% is prepared according to the formula specified 

 in "Standard Methods for the Examination of Water and Sewage"^ and "Stand- 

 ard Methods for the Examination of Dairy Products"^, and since 1933 our label 

 has carried a statement to that effect. 



When the medium is to be used in water purification plant control where 

 the inoculum is greater than 1 ml., particular care must be taken to preserve the 

 correct concentration of dye and bile in the medium after dilution with the 

 sample. The table given below indicates the quantity of dehydrated medium to 

 use per 1000 ml. distilled water to maintain the correct concentrations of dye 

 and bile. 



In the presumptive test for members of the coliform group in the examination 

 of dairy products a series of tubes of Brilliant Green Bile 2% are inoculated with 

 appropriate dilutions of the sample. Use 5 tubes of each solution. Select dilutions 

 to provide at least one positive and one negative tube in the series inoculated. 

 Incubate tubes for 48 hours at 35-3 7 °C. Gas formation constitutes a positive pre- 

 sumptive test. 



To rehydrate the medium, dissolve 40 grams of Bacto-Brilliant Green Bile 2% 

 in 1000 ml. of distilled water. The medium is distributed in fermentation tubes 

 and sterilized by autoclaving for 15 minutes at 15 pounds pressure (121°C.). The 

 final reaction of the medium will be pH 7.2. 



One pound of Bacto-Brilliant Green Bile 2% will make 11.3 liters of medium. 



Concentrations of Dehydrated Medium Required 

 to Maintain the Proper Concentration of Ingredients 



1 Standard Methods for the Examination ^ Am. J. Pub. Health, 10:874:1920. 



of Water and Sewage, gth Edition: 194:1946. « J. Am. Water Works Assoc, i8:337:i927. 



2 Standard Methods for the Examination 'J. Dairy Science, 15:321:1932. 



of Dairy Products, gth Edition: 152:1948. ^ Am. J. Pub. Health, 27:1243:1937., 



' Standard Methods for the Examination » Standard Methods for the Exammation 



of Water and Sewage, 9th Edition: 226:1946. of Water and Sewage, 9th Edition: 188:1946. 

 * Stain Tech., 1:129:1926. 



