270 A MANUAL OF THE ASPERGILLI 



Kojic Acid 



The ability of members of the A. flavus-oryzae group to produce kojic 

 acid has been recognized for more than three decades. It is only within the 

 past fifteen years, however, that serious attention has been given to this 

 fermentation. Beginning with the work of Challenger, Klein, and Walker 

 in 1929 and 1931, and continuing with that of May, Herrick, Moyer, Ward, 

 and Wells in 1931 and 1932, the proper nutrients and cultural conditions 

 necessary for its production were defined. Subsequent contributions have 

 been made by Kluyver and Perquin (1933) and by Barham and Smits 

 (1936). In all of the early reports the responsible cultures were cited as A. 

 oryzae, whereas in more recent ones the cultures employed have generally 

 been identified as Aspergillus flavus. It is of interest to note that the strain 

 studied by May and associates (NRRL No. 484: Thorn No. 3538) was a 

 thoroughly typical A . flavus when first isolated by Thorn in 1914, but during 

 the long period that it has been maintained in artificial culture it has gradu- 

 ally changed until today it more nearly resembles A . oryzae in its general 

 habit and coloration (fig. 72 C). Its capacity to produce kojic acid remains 

 undiminished, however. The culture employed by Barham (NRRL No. 

 625) likewise fails to satisfy the typical cultural picture of A . flavus, although 

 it is discussed under this name. In contrast to these cultures, other strains 

 belonging to this group have been under continuous laboratory cultivation 

 for more than 30 years without apparent change in appearance or behavior. 

 The above and additional references to the kojic acid fermentation are pre- 

 sented in the Topical Bibliography, pp. 297-298. 



Enzymes 



Members of the A . flavus-oryzae group produce diastatic and proteolytic 

 enzymes abundantly. For this reason they have been much studied, and 

 an extensive literature regarding mold enzymes has developed around the 

 use of these fungi. In large measure the alcoholic and soy food industries 

 of the Far East are based upon these molds and their enzymes. In the 

 production of alcoholic beverages, the diastatic enzymes produced by an 

 Aspergillus (regularly identified as A. oryzae) are employed to hydrolyze 

 the rice starch. Alcohol is then produced from the resultant sugars by the 

 addition of a fermentative yeast. In the soy industries, closely related 

 molds, or even the same strains, are used as a source of proteolytic enzymes. 

 In 1894 Takamine secured a series of U. S. patents covering the production 

 of diastatic enzymes and the making of alcoholic liquors (see Topical 

 Bibliography, p. 302). Subsequent to this, other investigators, mostly 

 Japanese, published a number of papers in this field. Oshima in 1922 and 

 1928 reported on the production of protease by members of the A. flavus- 



