MINERAL NUTRITION OF FUNGI 



The support and maintenance of optimum mycelial growth do 

 not constitute the only requirement of fungi for a proper balance 

 of salts. Pratt ( 1945) demonstrated that the synthesis of penicillin 

 by Fenicillium notatum is also conditioned by salt balance. By use 



100 



70 



60 50 40 



NaN0 3 ( percentage ) 



30 



20 



10 







Fig. 1. Graph of triangle system, showing percentage composition of differ- 

 ent solutions to be tested. The apex of each triangle represents the constant 

 molarity. Each number within a triangle corresponds to a culture or a 

 series of identical cultures. (After Pratt.) 



of the triangle system he made up a series of 65 different nutrient 

 solutions containing KH 2 P0 4 , MgS0 4 , and NaN0 3 in different 

 proportions and in such way as to have a total molar concentration 

 of 0.04. Each solution contained in addition lactose, corn-steep 

 liquor, zinc sulphate, and phenylacetic acid, and the pH was ad- 

 justed with NaOH to be the same as that of every other solution. 

 As a result Pratt found that the best yields of penicillin were 

 secured in solutions containing not less than 8 millimoles of 

 KH 2 P0 4 per liter and not more than 20 millimoles of NaN0 3 per 

 liter. The absolute concentrations of the three salts in the series 





