174 



Tannic Acid Fermentation 



VI. INFLUENCE OF THE ADDITION OF SUGAR. 



Effect of 5 per cent sugar. For these cultures solution A was 

 used to which was added in the one series tannic acid alone, and to 

 the other, tannic acid and cane sugar. Sugar was added at the 

 rate of 5 grams per 100 cc. of solution, and the amount of tannic 

 acid is indicated by the check. The cultures were made in liter 

 flasks, and 500 cc. of the solution were used for each. The flask 

 and contents were sterilized, inoculated and kept in the incubator 

 at a temperature which varied from 27°-30°C. The results of the 

 experiment given in table VI are in all cases obtained from dupli- 

 cate cultures. 



TABLE VI. 



CULTUHE NO. 



DURATION 



days 



TANNIC ACID 



IN CTJLTUBE 



SOLUTION 



LOSS IN 

 TANNIC ACID 



GALLIC ACID 

 IN CULTUHE 

 SOLUTION 



GAIN 

 OR LOSS OF 

 GALLIC ACID 



DRY 

 WEIGHT OF 



FUNGU8 



Series I. Solution A + tannic acid. 



Series II. Solution A + tannic acid + cane sugar. 



4 

 5 

 6 

 Check 



6.008 

 10.35 

 13.10 



The results of the experiment seemed at first surprising. Instead 

 of getting a protective action of the sugar with respect to the gallic 

 acid, and thereby an increased yield of gallic acid, the opposite 

 condition seemed to result. The yield of gallic acid was actually 

 less at the end of ten days in the solution containing sugar than in 

 the solution which lacked sugar, even though more of the tannic 

 acid was transformed in the former. At the end of twenty days 

 more gallic acid was left in the cultures of series II than in the corre- 

 sponding culture solutions of series I, and so a certain protective 

 action of the sugar is evident. At the end of thirty days practi- 

 cally all of the tannic acid and gallic acid had disappeared from 



