INULASE FORMATION IN ASPERGILLUS 



119 



results of this experiment are tabulated below. Twenty cul- 

 tures for each source of carbon were used. 



c. Effect of varying amounts of inulin, as the sole source of carbon 



on inulase formation 



It appears from the above described series of experiments that 

 of the substances employed as a source of carbon inulin is the 

 most effective in stimulating inulase formation. The question 

 naturally arises as to whether or not this is an effect which is 

 proportional to the mass of the inuHn present or whether it is 



TABLE 4 

 Showing the effects of various sources of carbon on inulase formatio7i 



FUNG.VL PREPARATIONS FROM CULTURES USING SOURCES 

 OF CARBON LISTED BELOW 



PERCENTAGE OF HYDROL- 

 YSIS OF INULIN BT 

 EQUAL UNITS OF FUN- 

 GAL ENZYME PREPA- 

 RATIONS 



Inulin 



Soluble starch 



Sucrose 



Maltose 



Glucose 



per cent 



11.64 

 7.03 

 5.50 

 5.46 

 2.49 



an effect, which depends upon the contact of the dissolved inu- 

 lin particles with the organism regardless of their concentration. 

 The first experiment to answer this question consisted in growing 

 Aspergillus on media containing as a source of carbon 0.1%, 

 0.2%, and 0.4% of inulin respectively. The small amount of 

 growth upon all of the cultures and the rapidity with w^hich the 

 carbohydrate disappears indicates that the small amount of 

 inulin present soon becomes the limiting factor in the growth of 

 the fungus. The dry weight of mycelium produced closely 

 parallels the amount of inulin present. From the results ob- 

 tained it appears that the stimulus for inulase formation is not 

 at all in proportion to the mass of inuhn present. The amount 

 of hydrolysis brought about by a definite weight of prepared 

 mycelium from the two sets of cultures containing 0.1% and 

 0.2% is almost the same. The amount of hydrolysis caused by 



