242 DIFGO MANUAL 



BACTO 



BRAIN HEART INFUSION AGAR (B418) 



DEHYDRATED 



Bacto-Brain Heart Infusion Agar is recommended as a solid medium for the 

 cultivation of fastidious pathogenic bacteria and fungi. A selective Brain Heart 

 Infusion Agar especially recommended for the isolation of fungi is obtained 

 by the addition of 20 units penicillin and 40 micrograms of streptomycin per ml. 

 of sterile melted medium at 45-50°C. A method to obtain these concentrations 

 of the antibiotics is given in the description of Bacto-Sabouraud Dextrose Agar 

 page 238. A complete discussion of Bacto-Brain Heart Infusion Agar is given 

 on page 90. 



BACTO 



MALT EXTRACT BROTH (B113) 



DEHYDRATED 



Bacto-Malt Extract Broth is prepared from Bacto-Malt Extract, according to 

 the directions given by Thom and Church.^ It is recommended as a liquid 

 medium for the cultivation of yeasts and molds and may be employed as a 

 sterility test medium to detect the presence of these organisms. 



The use of malt and malt extracts for the propagation of yeasts and molds is 

 quite common. Reddish^ described a culture medium prepared from malt extract 

 which was a satisfactory substitute for wort. Thom and Church, following the 

 formula of Reddish, used Bacto-Malt Extract, as a base. The carbohydrates 

 present in such media are well suited to the growth requirements of fungi, par- 

 ticularly if the reaction of the media is somewhat acid. Comparative tests have 

 shown that early and luxuriant growth will be initiated in Bacto-Malt Extract 

 Broth from inocula of yeasts and molds as small or smaller than those required 

 for other media, including broths prepared with honey. 



For the cultivation of molds, filter paper cones may be dipped into Malt 

 Extract Broth and sterilized in deep culture dishes containing a layer of the 

 medium. The molds are seeded upon the moist surface of the sterile cones. Thom 

 and Church advise a solution of 100 grams of Bacto-Malt Extract Broth in 900 

 ml. of distilled water. 



To rehydrate the medium, dissolve 15 grams of Bacto-Malt Extract Broth in 

 1000 ml. of distilled water. A more nutritious medium can be obtained by using 

 more Bacto-Malt Extract Broth per unit of water. 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 4.7. 



One pound of Bacto-Malt Extract Broth will make 30.2 liters of medium. 



^Thorn and Church: The Aspergilli, igaS. 2 Abst. Bact., 3:6:1919. 



BACTO 



NEUROSPORA CULTURE AGAR 



DEHYDRATED 



Bacto-Neurospora Culture Agar is recommended as a neutral medium for the 

 cultivation of fungi. A selective medium for this group of microorganisms may 

 be prepared by the addition of penicillin and streptomycin as discussed under 

 Bacto-Sabouraud Dextrose Agar page 238. A complete description of Bacto- 

 Neurospora Culture Aear is given on page 214. 



