FUNGI AS TEST ORGANISMS 211 



This medium was used for thiamine assay using Phycomyces blake- 

 sleeanus as the test fungus (Schopfer, 1945). 



Sucrose-Ammonium Tartrate-Ammonium Nitrate 



Sucrose 20 g. 



KH2PO4 1 g. 



MgS04-7H20 0.5 g. 



Ammonium tartrate 5 . g. 



NH4NO3 1.0 g. 



NaCl 0.1 g. 



CaCli 0.1 g. 



B 0.01 mg. 



Mo . 02 mg. 



Fe 0.2 mg., 



Cu 0.1 mg. 



Mn 0.02 mg. 



Zn 2.0 mg. 



Bio tin 5 Mg 



Distilled water to make 1,000 ml. 



This medium was used by Horowitz and Beadle (1943) and by Beadle 

 (1944) for the assay of choline and inositol by biochemical mutants of 

 Neurospora crassa. 



Glucose-Casein Hydrolysate 



Glucose 25 g. 



Casein hydrolysate equivalent to 2 g. casein 



MgS04-7H20 0.5 g. 



KH2PO4 l.Og. 



Fumaric acid 1 . 32 g. 



NaaCOs 1.12 g. 



Fe+ + + as sulfate 0.2 mg. 



Zn+ + as sulfate 0.2 mg. 



Mn+ + as sulfate 0.1 mg. 



Distilled water to make 1 liter 



This medium was used by Leonian and Lilly (1945) for the assay of 

 certain vitamins. Various deficient yeasts and filamentous fungi were 

 used as test organisms. This medium is suitable for testing fungi for 

 vitamin deficiencies. 



Preparing for an assay. In general, the compound being assayed 

 should be brought into aqueous solution before assaying. Many vita- 

 mins occur in a ''bound" condition and must be liberated before analysis. 

 The procedure used to liberate bound vitamins depends upon the vita- 

 min involved, as well as the nature of the substance being assayed. 

 Snell (1948) has listed tentative methods for the liberation of the various 

 vitamins. In general, acid or enzymatic hydrolysis is used. Proteins 

 are hydrolyzed before amino-acid assay. Acid hydrolysis is destructive 



