1923] 



KLOTZ — NITROGEN METABOLISM IN FUNGI 



317 



ditions the medium showed a tendency toward alkalinity. His 

 explanation was that the nitrate, under the influence of these 

 organisms, is reduced to nitrite and the liberated oxygen is 

 united with the reducing H to form hydroxyl ions which reduce 

 the hydrion concentration of the medium. With the conditions 

 reversed, employing constant C source (glycerine) and different 

 N sources, the change in the reaction of the medium was shown 

 to be due to the N source, (NH 4 ) 2SO* medium, for example, rising 

 in hydrion concentration from Ph 5.8 to 4.2. The change of 

 P H in protein and amino acid media was found very variable, 

 depending on the species of the organism cultured, the original 

 P H , and the C source. An available C source in a protein medium 

 favored the production of an acid reaction; this was thought to 

 be due to the effect of the carbohydrate on the N metabolism 

 and not to the formation of acids from the C source. Some 

 species always increased the [h] in such media, while others 

 lessened it. Leucine nearly always favored acidity. The [h] 

 of all media was shifted toward the optimum by these organisms. 

 Molliard ('18) studied the rate of consumption by Sterig- 

 matocystis nigra of glucose and ievulose, resulting from the in- 

 version of sucrose, in a modified Kaulin's solution. Sucrose was 

 added with HC1 in 2 different concentrations (290 mgm. and 310 

 mgm. HC1 per 150 ml. of medium) for the 2 series run. The 

 increase in acidity lowered the harvest of fungus, but increased 

 the consumption of sugar. The determinations made at 21 days 

 showed that all the glucose, but only about one-sixth of the 

 Ievulose, had disappeared. In his 1920 work on the effect of 

 reaction on the liberation of CO» from cultures of the same 



fungus Molliard varied the acidity with H,SOi and Na»COi, and 

 recorded the reaction in terms of normality of acidity or alkalinity. 

 Determinations of active acidity were not made. It was found 

 that the amount of CO» set free in respiration increased rapidly 

 from 0.1 N alkalinity to a maximum at 0.02 N alkalinity, then 

 diminished slowly to 0.06 N alkalinity, — beyond this very 

 rapidly. Oxalic acid was said not to be produced in the acidity 

 range greater than 0.02 N H,S0 4 , but steadily increased in pro- 

 duction as the medium was made more alkaline, reaching a 

 maximum at 0.06 N alkalinity. 





