The Characteristics of Uricase Production by a Hyphomycetes isolated from the Excrements of Cettia diphone cantans. II. The Effectiveness of Purines and Pyrimidines as Substrates

The effectiveness of purines and pyrimidines as substrates for the induced production of uricase was studied in F-1 strain of Hyphomycetes, in a medium containing casamino acids, as a good nitrogen source for the growth of this strain. The purines were incorporated into the cells at a relatively early stage of the growth and then the enzyme was induced from all the substrates. No other substrates were found more effective than uric acid. The relationship between the amount of added uric acid and uricase production was examined in the following two cases : (1) The maximum concentration of uric acid in the medium was increased to 0.08% by dissolving uric acid into alkaline solution before adding it into the direct medium. Under this condition, the uricase production increased in proportion to the concentration of uric acid added. (2) The amount of uric acid added in the basal medium was increased to 0.30%, beyond its solubility, and undissolved uric acid precipitated in the bottom of Fernbach's culture vessel. In this experiment, there was no distinct relationship between the amount of uric acid added and uricase production. The precipitated uric acid started to dissolve slowly into the medium during the culture and its concentration in the medium increased markedly during the cultured process. Increase in the solubilizing capacity of the medium to uric acid was also observed as in the basal medium.