Lewis Knudson 189 



amount of it present, the procedure was as follows: Either a 0.5 

 'per cent, a 0.75 per cent or a 1.0 per cent solution of tannic acid 

 was employed. To the flasks containing the solution were then 

 added equal weights of the pulverized mycelium, the enzymatic 

 activity of which was to be determined. There was also added, 

 as an antiseptic, 2 per cent toluene. The flasks containing the 

 solution and mycelium powder, being tightly stoppered, were then 

 incubated for a definite period and then the solution analyzed for 

 gallic acid according to Jean's^^ method. The relative increase 

 in the gallic acid is taken as a measure of the amount of tannase pres- 

 ent. 



IV. INFLUENCE OF CONCENTRATION OF SUGAR AND TANNIC ACID 

 ON PRODUCTION OF TANNASE. 



Influence of concentration of tannic acid on the amount of enzyme 

 produced. It was found in certain experiments,'^ in which 10 

 per cent sugar plus tannic acid had been added to the nutrient 

 solution, that the addition of sugar could not prevent the secre- 

 tion of the enzyme tannase by Aspergillus niger, but the secretion 

 by Penicillium sp. was markedly decreased. In order to deter- 

 mine the -miniTTinTin concentration of tannic acid which would 

 stimulate the formation of the enzyme tannase and also what 

 influence the concentration of tannic acid would have upon the 

 amount, of tannase produced within the organism, the following 

 experiment was made: Solution B was used, to which was added 

 10 per cent cane sugar. Liter flasks were employed, and to each 

 were added 500 cc. of the solution. The flasks were plugged and 

 sterilized, and when cool the tannic acid was added to each in vary- 

 ing amounts, as is indicated in the table. For inoculation the 

 method described by Hasselbring^" was employed, though 1 cc. 

 of the spore-containing water was used instead of a single drop. 

 These cultures were incubated at 28°C., and the felt was then 

 removed and treated according to the method described. In 

 determining the enzymatic activity of the mycelium powder 0.3 



18 F. Jean: Die Bestimmung des Tannins und der Gallussaure, Chem. 



Centralbl., 1900, pp. nm-OS. . ^ .u- . , • i^qtoi^ 



19 L. Knudson: Tannic acid Fermentation I, this Journal, xiv, p. 159, 191d. 

 "H. H. Hasselbring: Carbon Assimilation of Penicillium, Bot. Gazette, 



xlv, pp. 17fr-193, 1908. 



