As a series of studies on the nucleic acids and their related substances 210 samples were collected from 76 places such as farm soil, compost of heap, nuruk and meju to obtain microbial strains which produce 5´-phosphodiesterase.
From these samples total of 758 strains were isolated by the use of dilution pour plate method. For all isolated strains primary screening of tire productivity of RNA depolymerase was performed and useful strains with regard to 5´-phosphodiesterase productivities were identified.
For these useful strains optimum condition, the effect of various compounds on the activity of 5´-phosphodiesterase, and the optimum condition for enzyme reaction were discussed.
The quantitative of 5´-mononucleotides produced by the action of 5´-phosphodiesterase was performed using anion-exchange column chromatography and their identified was done by paper chromatography, thinlayer chromatography, ultra violet spectrophotometry, and characteristic color reaction using carbazole and schiff´s reagent.
(1) Penicillium citreo-viride PO 2-11 and Streptomyces aureus SOA 4-21 from soil were identified as a potent 5´-phosphodiesterase producing strains.
(2) Optimum culture conditions for Penicillium citreo-viride PO 2-11 strain isolated were found to be pH 5.0 and 30℃, and the optimum conditions for enzyme action of 5´-phosphodiesterase were pH 4.2 and 60℃.
Best carbon source for the production of 5´-phosphodiesterase was found to be sucrose and ammonium nitrate for nitrogen source. Addition of 0.01% corn steep liquor or yeast extract exhibited 20% increase in the amount of 5´-phosphodiesterase production compared to the control.
5´-phosphodiesterase produced by this strain was activated by Mg^(++), Ca^(++), Zn^(++), Mn^(++) and was inhibited by EDTA, citrate, Cu^(++), Co^(++).
5´-phosphodiesterase produced 5´-mononucleotide from RNA at a rate of 65.81%, and among the 5´-mononucleotides accumulated 5´-GMP only was found to have flavorous and the strain was also found lack of 5´-AMP deaminase.
Productivity of 9avorous 5´-GMP was found to be 186.7㎎ per gram of RNA.
(3) Optimum culture canditions for the isolated Streptomyces aureus SOA 4-21 strain were pH 7.0 and 28℃, and the optimum conditions for the action of 5´-phosphodiesterase were pH 7.3 and 50℃.
The best carbon source for 5´-phosphodiesterase production was found to be glucose and that of nitrogen was asparagine.
Addition of 0.01% yeast extract exhibited increased productivity of 5´-phosphodiesterase by 40% compared to the non-added control.
5´-phosphodiesterase produced by this strain was activated by Ca^(++), Zn^(++), Mn^(++) and was inhibited by citrate, EDTA, Cu^(++).
It was also found that the strain produce 5´-AMP deaminase in addition to 5´-phosphodiesterase. For this reason although decomposition rate was 63.58% the accumulation of 5´-AMP, 5´-CMP, 5´-GMP and 5´-UMP occurred by the breakdown of RNA.
In the course of these reaction 5´-AMP deaminase converted 60% of 5´-AMP thus produced into 5´-IMP and flavorous 5´-mono nucleotide production was significantly increased by this strain over the above mentioned one.
Production rates were found to be 171.8㎎ per grain of RNA for 5´-IMP and 148.2㎎ per gram of RNA for 5´-GMP, respectively.
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