176 



Tannic Acid Fermentation 



TABLE VII. 



CULTURE 

 NO. 



Check 



DURATION 



days 



GALLIC ACID 

 IN CULTURE SOLU- 

 TIONS 



INCREASE OF GAL- 

 LIC ACID 



2.198 



DRY WEIGHT OP 

 FUNGUS 



Aspergillus niger. 



• Transformation of tannic acid complete. 



t Considerable tannic add atlU left In culture solution. 



fication occurred. According to Malfitano'^ the secretion of the 

 enzymes from Aspergillus occurs just after fructification, and it 

 is possible to conclude that the lack of transformation is explain- 

 able by non-secretion of the enzyme by the submersed growth. 

 VanTieghem,^^ however, found that transformation was effected 

 when the growth was submersed; and some experiments of the 

 writer subsequently confirm the fermentation by submersed 

 growth. The non-transformation is probably due to the inhibiting 

 action of the sugar on the secretion of the enzyme tannase, but not 

 on the formation of the enzyme, for subsequent experiments have 

 shown that with 2 per cent tannic acid and 10 per cent sugar the 

 enzyme is formed. The inhibition of enzyme secretion by the 

 presence of organic nutrients has been observed by Puriewitsch.^' 



"G. Malfitano: La proteolyze chez I'Aspergillus niger, Ann. d. I'Inst. 

 Pasteur, xiv, pp. 60-81, 1900. 



" Loc. cit. 



"K. Puriewitsoh: Ueber die Spaltung der Glycoside durch die Schim- 

 melpilze,Ber. d. deulsch. hoi. Gesellsch., xvi, pp. 368-377, 1898. 



