INULASE FORMATION IN ASPERGILLUS 81 



hours, after which the Hquid portion is filtered off and used appar- 

 ently in combination with the liquid of the culture medium as the 

 source of inulase. Boselli finds that the secretion of inulase by 

 Aspergillus iiiger is ''notably constant/' and that, if equal 

 amounts of various carbohydrates are used in different cultures, 

 the amount of inulase secreted does not vary to any extent. He 

 also finds, as have other investigators, that the amount of en- 

 zyme secreted into the culture medium increases rapidly as 

 cultures become older. 



Work on the enzyme tannase has given results quite at vari- 

 ance with those obtained from the study of most other enzymes. 

 Fernbach (1890) finds that certain fungi when grown on Raulin's 

 solution in which the carbohydrates are replaced by tannin pro- 

 duce the enzyme tannase. Pottevin (1901) has also extracted 

 an enz^^me from fungi capable of hydrolyzing commercial tannin 

 to gallic acid and glucose. This enzyme is not formed except 

 when the fungi are grown on a tannin medium. 



Knudson (1913) has undertaken a more extensive studj^ of 

 tannic acid fermentation, studying principally, Aspergillus niger 

 and Penicillium sp. and finds that these fungi are able to fer- 

 ment tannic (gallo-tannic) acid, yielding gallic acid as an endprod- 

 uct. When these forms are grown on a modified Czapek's 

 solution containing tannic or gallic acid, supplemented by suc- 

 rose as a source of carbon, they form the enzyme tannase. In 

 the absence of tannic or gallic acid, no tannase is formed. Gal- 

 lic acid is not as efficient as tannic acid in stimulating the secre- 

 tion of tannase. Fourteen other substances used as a source 

 of carbon failed to stimulate the secretion of tannase. Experi- 

 ments, in which a constant amount of sucrose and various 

 amounts of tannic acid are used, show that the greater the amount 

 of tannic acid supplied the greater is the secretion of the enzyme. 

 When a constant amount of tannic acid is employed with vary- 

 ing amounts of sucrose, the increase in the amount of sucrose is 

 found to have an inhibitory effect on the amount of tannase se- 

 creted. Media having tannic acid as the sole source of carbon 

 are found to give a maximum secretion of tannase. The amount 

 of tannase secreted is regulated by the amount of tannic or gal- 



yLI»RARY)2 



