INULASE FORMATION IN ASPERGILLUS 



121 



d. Effect of inulin on inulase formation in the presence of glucose 



It seems clear from the above mentioned experimental data 

 that inulin is the most efficient substance used as a source of 

 carbon in stimulating inulase formation and also that glucose 

 is the least efficient of the substances used as a source of carbon 

 in stimulating inulase formation. It further appears very prob- 

 able that glucose is absorbed and assimilated by the fungus 

 without»the intervention of enzymatic action. If this be true, 

 glucose should then be much more readily assimilated than inulin 

 and providing that it be present in sufficient quantities to serve 



TABLE 6 

 Showing the effect of various concentrations of inulin as the sole source of carbon 



on inulase formation 



FrNG.U. PREPARATIONS FROM CULTURES USING SOURCES 

 OF CARBON LISTED BELOW 



Inulin cultures (1.0%), 

 Inulin cultures (1.5%). 

 Inulin cultures (2.0%). 



PERCENTAGE OF HYDROL- 

 YSIS OF INULIN BT 

 EQUAL UNITS OF FUN- 

 GAL ENZYME PREPA- 

 RATIONS 



per cent 



27.39 

 27.79 

 26.39 



as a source of carbon for the fungus, one would expect at least 

 on a priori grounds, that glucose would tend to counteract the 

 stimulatory effects of inulin. As will be seen from the literature 

 already- reviewed certain investigators have obtained similar 

 results with certain other enzymes. 



In order to test this last hypothesis, the following series of 

 cultures were set up and inoculated with spores of Aspergillus 

 niger: viz., series A containing 1% of glucose as the sole source 

 of carbon ; series B containing inulin with a carbon content equiv- 

 alent to that of the glucose of series A ; and series C having 0.5% 

 of glucose plus inulin which had a carbon content equivalent to 

 0.5% of glucose. Thus all the cultures contained an equal num- 

 ber of carbon atoms per unit volume. It was found that the two 

 sets of cultures containing inulin are appreciably stimulated at 

 the beginning of the growth period and further that they come 

 to sporulation some 24 hours before the cultures containing only 



^6« 



