Feb. i6, 1920 



Invertase Activity of Mold Spores 



539 



It is to be regretted that the inoculations differed so widely, for there 

 were 5,600,000 spores per cubic centimeter in the 10 to 40 per cent solu- 

 tions and only 220,000 spores per cubic centimeter in the 50 to 70 per 

 cent solutions. However, it is evident that with an increase in concen- 

 tration up to 50 per cent there is a marked loss in sucrose accompanied 

 by a corresponding increase in reducing sugars. Beyond this point the 

 loss in sucrose is not so significant. The same is true of the gain in reduc- 

 ing sugars. One may be permitted the speculation that had the inocu- 

 lation in the 50 to 70 per cent solutions been 25 times larger, the results 

 would have corroborated those previously obtained with the blue asper- 

 gillus — namely, that the invertase released by the spores of Penicillium 

 expansum was active in concentrations of sugar as high as the saturation 

 point and attained a maximum between the 50 and 60 per cent concen- 

 trations. 



In Table III are recorded the results obtained with Aspergilhis niger in 

 concentrations above 50 per cent sucrose, since we have previously indi- 

 cated an increase in invertase activity of the spores of this organism with 

 an increase in concentration.^ 



Table III. — Influence of concentration on the invertase activity of spores of Aspergil- 

 lus niger « 



Concentration. 



Polariza- 

 tion. 



Loss in 

 polariza- 

 tion. 



Loss in 

 sucrose. 



Reducing 

 sugars. 



Gain in 

 reducing 

 sugars. 



50 per cent, control 52 



50 per cent, with heated spores 



50 per cent, with spores 



60 per cent, control 



60 per cent, with spores 



70 per cent, control 



70 per cent, with spores 



Per cent. 



52- 

 40. 



57- 

 48. 

 66. 



57- 



II. 4 



9.6 



71 



II. 4 

 ■9.'6 



7-1 



Per cent. 

 I. 16 

 I. 40 

 6.94 



1. 71 

 6.67 



2. 13 

 5.18 



Per cent. 



O. 24 

 5-54 



4.96 



3-05 



» 680,000 spores per cubic centimeter were used. 



It will be seen from Table III that the percentages of sucrose lost and 

 of reducing sugars gained show a maximum at 50 per cent concentration 

 with Aspergillus niger, and that there is a diminished but significant 

 activity up to the saturation point as with the blue aspergillus and 

 Aspergillus niger. 



While it is indeed difficult to draw any comparative conclusions con- 

 cerning the invertase activity of the three molds under consideration, 

 because of the differences in the number of spores used for inoculation, 

 nevertheless it can safely be postulated that the spores of the blue asper- 

 gillus are relatively more active in inverting power than the other two 

 molds employed. For it will be seen that with 130,000 spores of this 



' KopELOPF, Nicholas, and Kopeloff, Lillian, the deterioration DP ovnb sugar by fungi. 

 Agr. Exp. Sta. Bui. 166, 71 p. 1919. Literature cited, p. 69-72. 



La. 



