INULASE FORMATION IN ASPERGILLUS 115 



are added to a solution of inulin. The primary aim in these 

 preliminary experiments was to ascertain whether or not there 

 was a definite stage in the life-history of the organism, at which 

 the greatest amount of enzyme was present in the mycelium. 

 For reasons to be discussed later, it seemed undesirable to attempt 

 to consider any enzymes which the culture medium might con- 

 tain thus making it especially desirable to have a definite cri- 

 terion for deciding w^hen the mycelium should be treated. As 

 has been pointed out above, practically all investigators have 

 found that the mycelium contains the greatest amount of en- 

 zymes at the beginning of the sporulation period. 



The purpose of the first experiment was to determine if possible 

 whether the greatest amount of inulase in the mycelium of As- 

 pergillus niger was at the beginning of the period of sporulation 

 or at some other period. Sixty-five cultures each containing 25 

 cc. of culture medium and 1% of inulin were inoculated and incu- 

 bated at 30°C. At the end of each of the following periods, thir- 

 teen cultures were removed and treated: viz., thirty-two hours, 

 forty-eight hours, seventy-four hours, ninety-six hours, one 

 hundred and twenty hours. 200 cc. of water were added to each 

 gram of the treated mycelium and 50 cc. of the solution of en- 

 zymes thus obtained used with each unit of the experiments. As 

 mentioned each unit of an experiment consisted of 250 cc. of 

 solution containing a definite amount of fungal extract and 1 

 gram of inulin. Digestion was continued at 40°C. for four hours. 

 The data tabulated below show that the greatest hydrolysis of 

 inulin was brought about by extracts from the forty-eight hour 

 cultures, at the end of which time sporulation had just begun. 

 Fungal extract from the thirty-two hour cultures was somewhat 

 less active than that from the forty-eight hour cultures. After 

 the beginning of sporulation the amount of enzyme present in 

 the mycelium fell off rapidly until at the end of a one-hundred and 

 twenty hours the amount of enzymatic activity was almost nil. 

 It thus appears that, w^hen sporulation begins, there occurs a 

 distinct falling off in the inulase content of the mycelium. The 

 following table summarizes the results of the experiment and 

 shows that the greatest amount of enzymatic activity per unit of 

 treated mycelium was at the beginning of the sporulation period. 



