STUDIES ON THE PROTEOLYTIC ENZYMES OF SOIL 

 FUNGI AND ACTINOMYCETES^ 



SELMAN A. WAKSMAN 



From the Department of Biochemistry, University of California 



Received for publication December 18, 1917 



The proteolytic enzymes of microorganisms have been studied 

 by a number of investigators ; but most of the data obtained are 

 merely qualitative in nature. A full bibliography on the inves- 

 tigations concerning bacterial enzymes can be found in the work 

 of Fuhrman (1907); the investigations of the enzymes of molds 

 have been reviewed by Wehmer (1907) and by Dox (1910). 

 Mention will here be made only of those investigations which 

 have a direct bearing upon the work at hand. 



ORGANISMS USED IN THE PRESENT STUDY 



A number of organisms isolated from different soils were used 

 for this work, although the greatest amount of work was devoted 

 to the first named organism. 



Aspergillus niger van Tieghem. This organism was isolated 

 from a sandy loam soil on the College Farm, at New Brunswick, 

 New Jersey. Methods of isolation and the description of soils, 

 for this as well as for the following organisms, can be found in 

 another place (Waksman, 1916). This organism was selected 

 for the work because many of the previous investigations on en- 

 zymes of molds have been conducted with it. Since its identifica- 

 tion is not difficult, we may suppose that previous investigators 

 used the organism originally described by van Tieghem, al- 

 though, as was recently shown by Thom (1916), the organism 



1 The data presented in this paper form Part II of the dissertation presented 

 by the author for the degree of Doctor of Philosophy, University of California, 

 December, 1917. 



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