214 DIFCO MANUAL 



BACTO 



NEUROSPORA CULTURE AGAR (B321) 



DEHYDRATED 



Bacto- Yeast Extract 5 g. 



Proteose Peptone No. 3, Difco 5 g. 



Bacto-Maltose 40 g. 



Bacto-Agar 15 g. 



Bacto-Neurospora Culture Agar was developed for the cultivation of Neuro- 

 spora to be used in microbiological assays as for example for the assays of pyri- 

 doxine and choline. It is recommended that the spores from a 48 hour culture of 

 Neurospora be used as an inoculum in such assays. This medium is also recom- 

 mended as a nearly neutral medium with 4 per cent maltose, for the cultivation 

 of a large variety of fungi. A selective medium for fungi may be prepared by the 

 addition of penicillin and streptomycin as discussed under Bacto-Sabouraud 

 Dextrose Agar page 238. 



To rehydrate the medium, suspend 65 grams of Bacto-Neurospora Culture 

 Agar in 1000 ml. 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.). Final reaction of the medium will be pH 6.7. 



One hundred grams of Bacto-Neurospora Culture Agar will make 1.5 liters of 

 medium. 



BACTO 



RIBOFLAVIN ASSAY MEDIUM (B325) 



DEHYDRATED 



Photolyzed Peptone 22 g, 



Yeast Supplement 2 g, 



Bacto-Dextrose 20 g, 



Sodium Acetate 1.8 g. 



/-Cystine, Difco 0.2 g, 



Dipotassium Phosphate 1 g. 



Monopotassium Phosphate 1 g. 



Magnesium Sulfate 0.4 g, 



Sodium Chloride 0.02 g 



Ferrous Sulfate 0.02 g 



Manganese Sulfate 0.02 g. 



Bacto-Riboflavin Assay Medium is a complete dehydrated medium for the 

 microbiological assay of riboflavin. It is free from riboflavin but contains all other 

 factors necessary for the growth of Lactobacillus casei e 7469 ATCC. The addi- 

 tion of riboflavin, in certain increasing concentrations, gives a growth response by 

 JL. casei e 7469 which may be measured acidimetrically or turbidimetrically. This 

 medium is a slight modification of the medium described by Snell and Strong^. 

 It is prepared according to the specifications given in the U. S. Pharmacopeia,^ 

 National Formulary^ and the Official Method of Analyses of the Association of 

 Official Agricultural Chemists* except that it contains 2 per cent anhydrous 

 dextrose in the basal medium instead of 6 per cent. Additional dextrose may 

 be added if desired, however, in our experience this causes carmelization during 

 the preparation of the medium with adverse effects on the assay procedure. The 

 lower concentration of dextrose has given parallel results. 



Best results, using Bacto-Riboflavin Assay Medium, have been obtained through 

 the use of the following procedure: 



