ENZYMES OF WOOD-DESTROYING FUNGI 43 



Production of enzymes by fungi. Scientific interest in the 

 production of enzymes by fungi had its beginning in Pasteur's 

 studies of the cause of fermentation. Of course, fermentation 

 had been utilized by man for centuries before Pasteur's time, but 

 no adequate explanation of the process had been offered. Pasteur 

 contended that fermentation was a biological process, not a 

 mechanical breakdown of the sugar molecule as Liebig believed, 

 and that it required the presence of living yeasts. The first proof 

 that enzymes produced by the yeasts induced alcoholic fermenta- 

 tion was offered in 1897, when Buchner extracted a fluid from 

 veast cells and caused sugars to be fermented w T ith this fluid. 

 Since then many studies of the enzymic activities of fungi, deal- 

 ing either with the enzyme-producing ability of certain species 

 or with the utilization of this ability in the production of end- 

 products of commercial importance, have been made. 



Methods for detection of enzymes. Two general methods 

 have been employed to determine the production of enzymes: 

 (a) the in vitro method, in which some portion of the fungus is 

 extracted in water and the enzyme is precipitated, the precipitate 

 then being dried to an "enzyme powder"; and (b) the in vivo 

 method, in which the fungus is cultivated on some chosen sub- 

 strate and in which utilization or nonutilization of the substrate can 

 be determined. Each method possesses advantages and disadvan- 

 tages over the other, and various modifications have been instituted 

 to make each more suitable for the problem in hand. In general, 

 the in vivo method, as described by Crabill and Reed (1915), is 

 open to less valid criticisms than the in vitro method. Among the 

 criticisms levelled against the in vitro method are: (a) extraction 

 diminishes the activity of enzymes; (b) the proteases may decom- 

 pose some of the other enzymes present in the extracted fraction; 

 and (c) certain enzymes, especially intracellular ones, may not act 

 outside the living cell; that is, the enzymic reactions characteristic 

 of the living organism cannot be duplicated with enzyme extracts. 



Enzymes of wood-destroying fungi. A brief summary of 

 essential knowledge regarding the enzymes produced by wood- 

 destroying fungi has been prepared by Bose (1939), who indicates 

 that Bourquelot and Herissey (1895) first directed attention to 

 this problem in 1895 in connection with their studies of Poly poms 

 sulphur eus. In 1899 Czapek (1899) discovered that Merulius 

 lacrymans is able to digest lignin by virtue of an enzyme that he 



