1 82 Tannic Acid Fermentation 



duced in this last was only 1.3 mgm., yet sufficient of the enzyme 

 was liberated to transform a quantity of tannic acid more than 

 2000 times the weight of the mycelium produced. 



From an economic standpoint the method of series I is wasteful 

 of gallic acid, as the organism utilizes much of this substance in its 

 metabolism. Series II has an advantage over series III, and series 

 III over series IV, only in the rapidity of the transformation. 

 The small amounts of growth in series III and IV require such a 

 slight amount of gallic acid in their metabolism that the yield of 

 galhc acid in those series would finally be practically equal to 

 that obtained in series II, to the cultures of which sugar had been 

 added. This fact is borne out by the larger amounts of tannic acid 

 left in the culture solutions of series II and series III. 



IX. SUMMARY. 



1. Tannic acid is toxic to a large number of fungi at relatively 

 low concentrations. 



2. Aspergillus niger is a more vigorous fermentative organism 

 than Penicillium sp. 



3. The fermentation was found to be more rapid in the gall 

 nut infusion than in the synthetic solution in which tannic acid 

 was the only source of carbon. The presence of other organic 

 compounds in the gall nut infusion protected to a certain extent 

 the gallic acid. 



4. The addition of 5 per cent sugar did not protect the gallic 

 acid but simply increased the growth. The addition of 10 per 

 cent sugar protected the gall'-C acid entirely. 



5. When galHc acid and cane sugar to the extent of 5.5 per cent 

 and 10 per cent, respectively, were offered together, the cane sugar 

 was elected and the gallic acid left in the culture solution. 



6. Fermentation can take place under anaerobic conditions, and 

 1 mgm. of mycelium is sufficient to effect the transformation of 

 2.706 grams of tannic acid in ten days. 



7. In an approximately 15 per cent solution of tannic acid, 

 fermentation was most rapid when the tannic acid alone served as 

 the source of carbon, and when aerobic conditions were main- 

 tained, yet the method of fermentation is wasteful from the stand- 

 point of an economical yield of gallic acid. 



