DEHYDRATED CULTURE MEDIA 73 



BACTO 



TOMATO JUICE AGAR (B31) 



DEHYDRATED 



Tomato Juice (400 ml.) 20 g. 



Bacto-Peptone 10 g. 



Bacto-Peptonized Milk 10 g. 



Bacto-Agar 11 g. 



Bacto-Tomato Juice Agar is recommended for the direct plate count and cul- 

 tivation of Lactobacilli. It is an excellent plate medium for determining the 

 relative numbers of organisms in acidophilus products and for estimating the 

 degree of intestinal implantation. 



The Lactobacilli grow poorly on ordinary culture media and require special 

 nutrients. Mickle and Breed^ reported the use of tomato juice in culture media 

 for Lactobacilli, and Kulp,^ while investigating the use of tomato juice on bac- 

 terial development, found that the growth of L. acidophilus was enhanced in 

 media containing this material. Colonies on plates of this new medium were 

 large and more characteristic than on other media. Later Kulp and White^ 

 described a modification of the original medium which gave them relatively 

 high quantitative counts. 



Bacto-Tomato Juice Agar is prepared according to Kulp and White's modi- 

 fication and contains Bacto-Peptone and Bacto-Peptonized Milk. The dehydrated 

 medium is excellently suited for the cultivation of members of the Lactobacillus 

 group. 



To rehydrate the medium, suspend 51 grams of Bacto-Tomato Juice Agar in 

 1000 ml. of cold distilled water and heat to boiling to dissolve the medium com- 

 pletely. Distribute in tubes or flasks and sterilize in the autoclave for 15 minutes 

 at 15 pounds pressure (121°C.). The final reaction of the medium will be 

 pH 6.1. 



One pound of Bacto-Tomato Juice Agar will make 8.9 liters of medium. 



iTech. Bull, no, N. Y. State Agr. 2 Science, 66:512:1927. 



Exp. Sta., 1925. 3 Science, 76:17:1932. 



BACTO 



TOMATO JUICE AGAR SPECIAL (B389) 



DEHYDRATED 



Tomato Juice (400 ml.) 20 g. 



Bacto-Peptone 10 g. 



Bacto-Peptonized Milk 10 g. 



Bacto-Agar 20 g. 



Bacto-Tomato Juice Agar Special is recommended for the direct plate count 

 of the Lactobacilli from saliva and for the cultivation of other acidophilic 

 microorganisms. It is prepared according to the formula suggested by Jay.^-^ The 

 number of Lactobacilli in saliva is an index of predisposition to dental caries as 

 described by Jay.^-^ Many dentists prefer to use the direct count of Lactobacilli 

 for the diagnosis of caries rather than the colorimetric method using Bacto- 

 Snyder Test Agar, as described on page 190. 



The reaction of Bacto-Tomato Juice Agar Special is adjusted to pH 5.0 so as 

 to encourage the growth of Lactobacilli and at the same time inhibit the growth 

 of many commensal bacteria that may be encountered in saliva. This is a 

 slightly more selective medium for Lactobacilli than is Bacto-Tomato Juice Agar 

 or Bacto-Trypsin Digest Agar described on page 74. 



