MISCELLANEOUS MINOR FERMENTATIONS 227 



o 



c 



/ \ 



HC COH 



II II 



CH2OHC CH 



\ / 

 O 



Kojic Acid 



Since the initial reports of these Japanese workers, numerous papers 

 have appeared on various aspects of the fermentation. Originally 

 isolated as a by-product of the fermentation of steamed rice by an 

 organism of the Aspergillus flavus-Oryzae group, it has since been 

 found that several species of Aspergillus, Penicillium Daleae, and 

 certain bacteria (species of Acetobacter) form it. 



A large number of compounds can serve as the source of carbon, 

 but the highest yields have been obtained by fermentation of glucose 

 or xylose. Ammonium salts, especially ammonium nitrate, serve as 

 good sources of nitrogen. Fermentations have been carried out over 

 the pH range of 2.0 to 5.0 depending upon the organisms with which 

 the individual investigators were working. Most of the studies have 

 been carried out at temperatures ranging from 20° to 35° C, but 

 May and his associates ^^ recommend a range from 30° to 35° C. 

 Depending on a number of factors, i.e., the mold species, incubation 

 temperature, pH, salts, the fermentation generally requires from 7 to 

 20 days for completion. Yields of over 50 per cent have been re- 

 ported by several investigators. May and his associates ^* observed 

 that ethylene chlorohydrin when added in fairly low concentrations 

 (0.01 per cent) markedly increases the yield of kojic acid in a fer- 

 mentation period of 10 days. ( 



Numerous mechanisms for the formation of kojic acid have been 

 proposed. Yabuta and others have suggested that glucose is oxidized 

 and dehydrated to kojic acid in the following manner. 



O 



II 

 HCOH C 



/ \ / \ 



HCOH HCOH ,10 HC C-OH 



I I ^ II II "I 3H2O 



CH2OH— CH HCOH ~^^° CH2OH— C CH 



\ / \ / 



O o 



Glucose Kojic acid 



