THE FORMATION OF KOJIC ACID BY ASPERGILLUS ORYZAE

Abstract

(1) The influence of the concentrations of glucose or glycerol and of (NH4)2SO4 on the formation of kojic acid by Aspergillus oryzae was observed. More kojic acid was formed with the medium containing a least amount of (NH4)2SO4 and a greater amount of glucose or glycerol. (2) The optimum pH for the formation of kojic acid was found to be about 2.4, and for the growth of the mould was about 5.0. (3) With 20 days' culture containing 5% of various substanses (in the cases of trioses 0.8% solutions were used), 0.05% (NH4)2SO4 and the other mineral matters, the formation of kojic acid was compared. (4) While the yield of the acid differed due to the nature of the substances, kojic acid was obtained with various carbohydrates, polyhydric alcohols and with gluconic acid. Neither with α-methyl glucoside, rhamnose, fatty acids, ketonic acids, aldehydes, ketones, monohydric alcohols, ketonic alcohols nor with amino acids, the formation of kojic acid was observed. (5) Among various carbohydrates, a considerable amount (40_??_10%) of kojic acid was obtained with maltose, cane sugar, glucose, inulin, fructose and with xylose, a less amount (6_??_1%) with mannose, arabinose and with galactose, while any formation was observed neither with lactose, glyceraldehyde nor with dihydroxyacetone. (6) Among polyhydric alcohols, formation of kojic acid was observed with sorbitol, dulcitol, glycerol, glycero-β-phosphate and with inositol, but neither with mannitol, erythritol nor with ethylene glycol. (7) With gluconic acid kojic acid was obtained, but with saccharic acid, glyceric acid or with various monohydroxy acid the formation was not observed. (8) It is suggested that the effect of Na2CO3 or Na2SO3 in diminishing the formation of kojic acid from various substances is attributable to the change in pH value of the medium. Department of Agriculture, Kyoto Imperial University.