AMERICAN 
JOURNAL OF BOTANY 
Vol. X April, 1923 No. 4 
PECTINASE IN THE SPORES OF RHIZOPUS 
J. L. Weimer and L. L. Harter 
(Received for publication April 28, 1922) 
Kopeloff and Kopeloff 1 showed that the deterioration of cane sugar 
depends in part at least on the hydrolyzing power of an enzym which is 
contained in the spores of such fungi as Aspergillus niger\ an Tiegh., A. 
sydowi Bain., and to a lesser extent Penicillium expansum Link and 
Aspergillus flavus Link. Harter and Weimer 2 also demonstrated that the 
spores of Rhizopus tritici Saito and R. nigricans Ehrb. contain an enzym ca¬ 
pable of hydrolyzing starch to reducing sugars. 
Pectinase production has been the subject of extensive researches by 
Harter and Weimer. 3 They found that this enzym is produced by several 
species of Rhizopus; that some of it is retained in the mycelium, and that a 
portion is exuded into the substratum. In their experiments, raw sweet- 
potato discs immersed in the substratum or in a watery extract of the my¬ 
celium were macerated so that coherence of the cells was entirely lost. The 
dissolution of the middle lamellae was in every way analogous to that 
produced by the action of the fungus itself in the host tissue. The enzym 
was found produced most abundantly in cultures two to three days old. 
They proved, moreover, that the enzym is secreted very early in the ger¬ 
mination of the spore. In fact, maceration of raw sweet-potato discs took 
place slowly when suspended in a nutrient solution in which spores of 
Rhizopus tritici had been placed for only eight hours. At the end of this 
time a considerable percentage of the spores had germinated, the germ 
tubes varying in length from one to ten times the diameter of the spores. 
The writers, after having shown that pectinase is exuded into the solution 
on which the fungus grew and that it is present in the mycelium, undertook 
to demonstrate the presence or absence of the enzym in the ungerminated 
spores. 
1 Kopeloff, N., and Kopeloff, L. Do mold fungi contain enzymes? Jour. Agr. Res. 
18: 195-209. 1919. 
2 Harter, L. L., and Weimer, J. L. Amylase in the spores of Rhizopus tritici and Rhi¬ 
zopus nigricans. Amer. Jour. Bot. 10: 89-92. 1923. 
3 Harter, L. L., and Weimer, J. L. Studies in the physiology of parasitism with special 
reference to the secretion of pectinase by Rhizopus tritici. Jour. Agr. Res. 31: 609-625. 
1921. Lit. cit., pp. 624, 625. 
[The Journal for March (10 : 113-166) was issued March 30, 1923]. 
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