DEHYDRATED CULTURE MEDIA 81 



BACTO 



VEAL INFUSION MEDIUM (B40) 



DEHYDRATED 



Veal, Infusion from 500 g. 



Proteose Peptone, Difco 10 g. 



Bacto-Agar 1 g. 



Bacto-Veal Infusion Medium is prepared from selected lean veal, and is 

 recommended as a liquid medium for the growth of anaerobes as well as many 

 other bacteria generally considered difficult to cultivate. The medium contains 

 0.1 per cent agar which provides, in freshly heated media, various degrees of 

 oxygen tension making possible the growth of anaerobes without special condi- 

 tions. 



The advantages of a medium with a low agar concentration, and Its influence 

 on the development of bacteria, particularly the anaerobes, has been described 

 by Kitchens^. In a broth, to which 0. 1 per cent agar has been added, there is a 

 clear upper zone well suited for aerobic growth; below this the flocculent agar 

 develops variable degrees of oxygen tension. This condition makes the medium 

 suitable for the growth of either aerobic or anaerobic bacteria. Falk, Bucca, and 

 Simmons^ point out the advantages of the use of small quantities of agar 

 (0.06-0.25 per cent) in the detection of contaminants in the sterility testing of 

 biologicals. They show that the growth of even common forms, such as the hay 

 bacillus and staphylococci, ordinarily considered easy to cultivate, was aided by 

 the presence of a small quantity of agar, and that growth is initiated in a much 

 shorter incubation period in such media. Since their experiments showed little 

 difference between 0.1 and 0.25 per cent agar, they used 0.1 per cent agar in 

 their routine tests, which is the quantity employed in Bacto-Veal Infusion 

 Medium. In the report on culture media for non-acid products, Cameron^, as 

 associate referee, recommended Bacto-Veal Infusion Medium for use in the 

 examination of canned meat. He reported this medium to be excellent as an en- 

 richment for the propagation of anaerobes. 



To rehydrate the medium, suspend 23 grams of Bacto-Veal Infusion Medium 

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

 completely. Distribute in tubes 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. 



For best results, Bacto-Veal Infusion Medium should be freshly prepared. If 

 the medium is not used the same day as sterilized, heat in boiling water or 

 flowing steam for a few minutes to remove absorbed oxygen and then cool 

 quickly without agitation, just prior to inoculation. 



One pound of Bacto-Veal Infusion Medium will make 19.7 liters of medium. 



1 J. Infectious Diseases, 29:390:1921. 3 Assoc. Official Agr. Chem., 20:429:1937. 



2 J. Bact., 37:121:1939. 



BACTO 



VEAL INFUSION BROTH (B344) 



DEHYDRATED 



Bacto-Veal Infusion Broth is identical to Bacto-Veal Infusion Medium except 

 the small concentration of agar has been omitted. This infusion medium is suited 

 for the cultivation of fastidious pathogenic microorganisms. "Standard Methods 

 for the Examination of Dairy Products"^ describe a Veal Infusion Broth, pre- 

 pared from finely ground veal and 0.5 per cent Bacto-Tryptone, for the cultiva- 

 tion of pathogenic streptococci. 



