INVERTASE ACTIVITY OF MOLD SPORES AS AFFECTED 

 BY CONCENTRATION AND AMOUNT OF INOCULUM 



By Nicholas Kopelopp, Bacteriologist, and S. Byall,' Assistatit Chemist, 

 Department of Bacteriology, Louisiana Sugar Experiment Station 



It has previously been shown " that mold spores may release sufficient 

 invertase to cause an appreciable inversion in lo and 20 per cent sucrose 

 solutions. This phenomenon was studied in connection with the dete- 

 rioration of cane sugar by fungi ^, but in considering its bearing upon the 

 latter problem it becomes imperative to establish the limits of concen- 

 tration at which the invertase of mold spores is active. The work of 

 O'Sullivan and Thompson "* is responsible for the claim that invertase 

 is not active in sucrose solutions above 40 per cent. The writers have 

 been unable to find in the literature any contrary stand, although there 

 exists some indirect evidence on this point. Since the film surrounding 

 the sugar crystal capable of supporting biologic activity must vary in 

 concentration from a supersaturated solution down to comparatively 

 low concentrations (depending upon the amount and distribution of the 

 moisture present), it was considered advisable to employ concentrations 

 of 10, 20, 30, 40, 50, 60, and 70 per cent, at an incubation temperature 

 of 48° to 50° C. for three days. The spore suspensions were prepared 

 according to the method previously described.^ 



The experiment with blue aspergillus^ is reported in Table I. 



In Table I are presented the averages of closely agreeing triplicate 

 determinations obtained with the spores of the blue aspergillus, at the 

 rate of 144,000 spores per cubic centimeter for 10 to 40 per cent solutions 

 of pure sucrose, and 1 30,000 spores per cubic centimeter for 50 to 70 per 

 cent solutions. It will be noted that with an increase in concentration 

 up to 60 per cent there is a proportional loss in percentage of sucrose 

 and correponding increase in reducing sugars. Beyond this point the 

 amount of inversion decreases. This brings out two important facts — 

 namely, that the invertase in the- spores of this mold is active in a sugar 

 solution at the point of saturation, and furthermore that the maximum 

 activity occurs between 50 and 60 per cent concentration for such an 

 inoculation. It may be mentioned, parenthetically, that the polarization 



' The authors are indebted to Lillian Kopeloff and the Station staff for many valuable suggestions. 



' Kopeloff, Nicholas, and Kopeloff, Lillian, do mold spores contain enzyms? In Jour. Agr. Re- 

 search, V. 18, no. 4, p. 195-209- 1919. 



' THE deterioration of cane sugar by fungi. La. Agr. Exp. Sta. Bui. i66, 73 p. 



1919. Literature cited, p. 69-72. 



* O'SuLLFVAN, C, and Thompson, Frederic'c W. invertase: a contribution to the rasTORY op an 

 enzyme or unorganized ferment. In Jour. Chem. Soc. London, v. 57. P- 834-931. 4 pi. 1890. 



•' Now identified as Aspergillus sydowi Bain. 



Journal of Agricultural Research, Vol. XVIII, No. 10 



Washington, D. C. Feb. 16, 1919 



tr Key No. La. -: 



(537) 



