DEHYDRATED CULTURE MEDIA 145 



colony surrounded by an intense yellow-green zone. Bacto-Brilliant Green Agar 

 is highly recommended for the isolation of Salmonella. However, it is not suitable 

 for the isolation of S. typhosa or Shigella organisms. Some strains of S. typhosa 

 will develop on this medium forming colonies identical to other Salmonella. 

 Some strains of Proteus may also grow forming red colonies. In the routine exam- 

 ination of stools, rectal swabs or other materials for the Gram-negative intestinal 

 pathogens, other primary plating media such as Bacto-S S Agar, Bacto-Bismuth 

 Sulfite Agar and Bacto-MacConkey Agar, as well as fluid enrichments such as 

 Bacto-Tetrathionate Broth and Bacto-Selenite Broth, should be used with Bacto- 

 Brilliant Green Agar. 



To rehydrate the medium, suspend 58 grams of Bacto-Brilliant Green Agar in 

 1000 ml. 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°G.). A longer period of sterilization will tend to de- 

 crease the selectivity of the medium. 



The final reaction of the medium will be pH 6.9. 



One pound of Bacto-Brilliant Green Agar will make 7.8 liters of medium. 



iBrit. J. Exp. Path., 6:291:1925. * Military Surgeon, 99:770:1946. 



3Zeit. Hyg., 117:26:1935. ^Personal Communication, 1947. 



"Am. J. Pub. Health, 34:1071:1944. 



BACTO 



LITMUS LACTOSE AGAR (B81) 



DEHYDRATED 



Bacto-Beef Extract 3 g. 



Bacto-Peptone 5 g. 



Bacto-Lactose 10 g. 



Bacto-Agar 10 g. 



Bacto-Litmus 1 g. 



Bacto-Litmus Lactose Agar has been used in water bacteriology and in othcf 

 examinations for the detection of members of the coliform group. This medium 

 may also be used for the determination of the fermentation of lactose with the 

 production of acid and gas. 



Litmus Lactose Agar, originally described by Wurtz in 1892, is one of the" 

 oldest of the differential plate media. It has been employed in the past and is still 

 being used, to a slight extent, in water bacteriology and other examinations for 

 the detection of members of the coliform group. Upon this medium, colonies of 

 the lactose fermenting bacteria are surrounded by a red zone which distinguishes 

 them from colonies of other organisms that either do not change the surrounding 

 medium or make it more intensely blue due to production of ammonia. 



Bacto-Litmus Lactose Agar is prepared according to the generally accepted 

 formula for this medium; when made up for use it contains 1 per cent of lactose 

 and 0.1 per cent of Bacto-Litmus. 



Bacto- Violet Red Bile Agar as discussed on page 61 is recommended for use 

 in making coliform counts of water, milk, dairy and other food products. Bacto- 

 Brilliant Green Bile Agar as discussed on page 52 is also a satisfactory medium 

 for counts of the coliform bacteria in water. 



To rehydrate the medium, suspend 29 grams of Bacto-Litmus Lactose 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°G.). The final reaction of the medium will be pH 7.0. 



One pound of Bacto-Litmus Lactose Agar will make 15.6 liters of medium. 



