DEHYDRATED CULTURE MEDIA 99 



Bacto-Liver Veal Agar is especially well suited for the isolation and cultiva- 

 tion of anaerobes. The medium may be used in anaerobic culture dishes or in 

 deep tube culture. 



Numerous methods for the cultiv^atlon of anaerobes have been devised and 

 many media have been proposed for this purpose. The use of the anaerobic 

 culture dish as described by Spray^'- is one of the procedures suggested for the 

 propagation of these organisms. Medium prepared from Bacto-Liver Veal Agar 

 is identical with the medium described by Spray^-* for use in his anaerobic 

 culture dishes for cultivation of anaerobes. 



Bacto-Liver Veal Agar gives excellent growth of the sporulating anaerobes. In 

 a personal communication Spray reported the usefulness of this medium for 

 isolation purposes since Clostridium perfringens colonies were fished within 6 

 hours from time of inoculation and C. tetani within 8 hours. Gas production is 

 inhibited when the medium is inoculated sparingly. With proper dilution giv- 

 ing 10-15 colonies per plate, primary isolations of pure cultures are readily ob- 

 tained. The medium may also be used in deep tube cultures of the sporulating 

 anaerobes. Bacto-Liver Veal Agar is also suitable for the routine isolation and 

 cultivation of many aerobes. 



To rehydrate the medium, suspend 97 grams of Bacto-Liver Veal 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°C.). The final reaction of the medium will be pH 7.3. 



When it is used in the anaerobic dish, Spray^ recommends that unless taken 

 directly from the sterilizer, the medium should be boiled for 10 minutes and then 

 cooled to 50° C. without agitation. Serial inoculations are then made and the 

 medium is poured into the dishes. After solidification, 5 ml. sterile Liver Veal 

 Agar is poured over the medium as a cover layer to prevent the spreading of 

 surface colonies. 



One pound of Bacto-Liver Veal Agar will make 4.6 liters of medium. 



^J: 



Lab. Clin. Med., 16:203:1930. 'Personal Communication. 



Bact., 21:23:1931. *J. Bact., 32:135:1936. 



PEPTONE MEDIA 



{Without Infusions) 



Infusions of meat with added peptone have been employed consistently as 

 culture media for bacteria. Extractives from fresh meat have been considered 

 essential in media for all but the most common organisms. In many cases, due 

 to ease of preparation and demand for greater uniformity in media, beef extract 

 has replaced the infusion of fresh meat. Media containing peptone without meat 

 extractives have been used for the routine cultivation of some of the more hardy 

 laboratory strains, or for routine tests such as the production of indole, methyl 

 red test, etc. Peptones have been used in semi-synthetic broths for the production 

 of diphtheria and scarlet fever toxin. 



The opportunities for variation in media prepared from fresh meat are ob- 

 vious. The freshness of the meat used in the infusion influences the amount of 

 muscle sugar present in the final medium. The age of the animal, the cut of the 

 meat, amount of trimming, time and conditions of infusion are further factors 

 contributing to variability of the final media. Likewise, the infusion of meat is 

 laborious, time consuming and costly. These conditions were recognized by the 



