AMYLASE OF RHIZOPUS TRITICI, WITH A CONSIDERA- 

 TION OF ITS SECRETION AND ACTION 



By L. L. Harter 



Pathologist, Cotton, Truck, and Forage Crop Disease Investigations, Bureau of Plant 

 Industry, United States Department of Agriculture 



INTRODUCTION 



That certain mold fungi secrete amyclastic and other enzyms has 

 been known for a long time. However, much of the work in this direc- 

 tion has been centered around a few common forms, especially in the 

 genera Aspergillus and Penicillium. In fact, the same organism has 

 been selected by many investigators who studied the same or different 

 phases of enzymic production. The literature on the subject is already 

 very large and has been reviewed and listed in many of the publications 

 of recent years. For this reason the writer will refer only to such arti- 

 cles in the body of the paper as are germane to the particular subject 

 under discussion. 



Rhizopus tritici was used for this investigation because it is responsible 

 for large losses of sweet potatoes and other vegetables under storage 

 and transportation conditions. Its parasitism has been proved repeat- 

 edly by inoculations into sweet potatoes, where it causes a rot identical 

 in appearance with that produced by R. nigricans. Preliminary ex- 

 periments were made with R. nigricans, which showed that it produces 

 amylase in abundance. No attempt has been made to duplicate with 

 R. nigricans the experiments carried out with R. tritici. So far as the 

 writer is aware these are the first experiments of the kind conducted with 

 R. tritici. 



Some of the work of other investigators has been duplicated as far 

 as the method employed would permit, the purpose being to compare 

 Rhizopus tritici with some of the fungi hitherto studied. Some of the 

 results of previous investigators were corroborated, while others were 

 not, which indicates that no sweeping generalizations regarding all 

 fungi can be drawn from the study of a single organism. 



METHOD OF EXPERIMENTATION 



The investigations were carried out mostly with the powdered mycelium, 

 although the diffusion of the enzym into the culture solution was not 

 entirely disregarded. For certain phases of the work extracts of the 

 mycelium were used. The fungus was grown on a modified Czapek's 

 nutrient solution or on sweet potato bouillon for most of the comparative 



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



Washington, D. C Feb. 15, 1921 



wu Key No. G-220 



(761) 



