DEHYDRATED CULTURE MEDIA 61 



One pound of Bacto-Formate Ricinoleate Broth will make 28.3 liters of 



medium. 



Concentrations of Dehydrated Medium Required 

 to Maintain the Proper Concentration of Ingredients 



1 Standard Methods for the Examination * J. Bact., 29:26:1935. 

 of Dairy Products, 9th Edition: 131 : 1948. ^ j. Bact., 29:23:1935. 



2 Standard Methods for the Examination *• J. Milk Tech., 8:323:1945. 



of Water and Sewage, 9th Edition: 188: 1946. 'Standard Methods for the Examination 

 2 Standard Methods for the Examination of Water and Sewage, 9th Edition: 226: 1946. 



of Dairy Products, 9th Edition: 133: 1948. 



BACTO 



VIOLET RED BILE AGAR (B12) 



DEHYDRATED 



Bacto- Yeast Extract 3 g. 



Bacto-Peptone 7 g. 



Bacto-Bile Salts No. 3 1.5 g. 



Bacto-Lactose 10 g. 



Sodium Chloride 5 g. 



Bacto- Agar 15 g. 



Bacto-Neutral Red 0.03 g. 



Bacto-Grystal Violet 0.002 g. 



Bacto-Violet Red Bile Agar is recommended for the direct plate count of 

 coliform bacteria in water, milk, dairy and other food products. "Standard 

 Methods for the Examination of Dairy Products"^ recommends the use of Violet 

 Red Bile Agar for the ml. coliform count in milk and other dairy products. In 

 Appendix I of "Standard Methods for the Examination of Water and Sewage"^ 

 this medium is suggested as a selective agar medium for direct plating of water 

 for members of the coliform group. 



The original work by Difco Laboratories on the development of a solid selec- 

 tive medium for the quantitative estimation of the number of viable coliform 

 organisms in water, milk, dairy and other food products was undertaken in 1932 

 in cooperation with M. H. McCrady, at that time sub-referee of the committee on 

 Standard Methods of Milk Analysis of the American Public Health Association. 

 The formula adopted had exhaustive trials in our laboratories and was also used 

 extensively by others in the determination of the presence and numbers of coli- 

 form organisms in milk and dairy products. The use of Bacto-Bile Salts No. 3 in 

 place of Bacto-Bile Salts originally employed resulted in an improved medium. 



Bacto-Violet Red Bile Agar is especially applicable to the control of pasteuri- 

 zation of milk and cream. The use of this medium makes it possible to determine 

 quantitatively the coliform count of the milk at any stage of the process. There- 

 fore, it is possible to determine the cleanliness of apparatus and the efficiency of 

 the process as well as to detect sources of contamination at various stages. 



