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Preparation of an enzyme (H) specific for dephosphorylation of phosphorylated streptomycin, a precursor of streptomycin, was obtained from mycelium of Streptomyces griseus.Previously, cell homogenate of the organism was employed as the source of H enzyme, but its purification was embarrassed by the proteinous contaminants in the homogenate. In the present investigation, it was found that 70 to 80% of H enzyme in mycelium could be extracted into medium merely by suspending the mycelium in 20% sucrose solution for several hours. The centrifuged supernatant of this suspension was much less contaminated with other proteinous materials, compared with other extraction methods. Column chromatography of the supernatant on Sephadex A-50 gave a peak of H enzyme which had 50 times as much specific activity as that in cell homogenate, while purification of the enzyme from cell homogenate by an procedure including salting out, dialysis and column chromatography on DEAE-Cellulose gave only 29 times increase in specific...

A natural precursor (L) of streptomycin which had no antibiotic potency was obtained from mycelium suspension of Streptomyces griseus in glucose solution and was transformed to streptomycin by H enzyme obtained from mycelium of the organism. This transforming reaction was carried out most effectively at slightly alkaline pH and inhibited by inorganic phosphate and ethylenediaminetetraacetate. L component was considered to be a phosphorylated compound and liberation of the phosphoric acid was essential for L component to be transformed to streptomycin. This transformation was performed not only by H enzyme but also by intestinal alkaline phosphatase, although some difference in the reaction mechanism was supposed to be between those two enzymes.

Forty-four bacterial isolates were subjected to screening test for production of antibiotic substance from kerosene. Twenty-two isolates were found to produce antibiotic substance : 19 isolates against Streptomyces and 3 isolates against bacteria. But no isolates produced any antibiotics against moulds and yeasts.

A natural precursor (L) of streptomycin which had no antibiotic potency was obtained from mycelium suspension of Streptomyces griseus in glucose solution and was transformed to streptomycin by H enzyme obtained from mycelium of the organism. This transforming reaction was carried out most effectively at slightly alkaline pH and inhibited by inorganic phosphate and ethylenediaminetetraacetate. L component was considered to be a phosphorylated compound and liberation of the phosphoric acid was essential for L component to be transformed to streptomycin. This transformation was performed not only by H enzyme but also by intestinal alkaline phosphatase, although some difference in the reaction mechanism was supposed to be between those two enzymes.

Investigation was carried out on demonstration of two substances constructing a precursor system located at a late stage of streptomycin biosynthesis by Streptomyces griseus. One of them is thought to be a natural precursor of Streptomycin(L) and the other is suggested as an enzymatic substance(H) transforming L to streptomycin. Both substances had no antibiotic potency and H was inactivated at low pH. L was obtained from a cell-free supernatant (active supernatant) prepared from suspension of young mycelium of Streptomyces griseus in glucose solution. H was obtained not only from active supernatant but also from cell-free extract of the organism.Two ways of isolation were established for L. Active supernatant was adsorbed on a CM-cellulose column equilibrated with 0.05 m Tris-maleate buffer (pH 8.0). Elution of this column with the same buffer as was used for equilibration gave L-containing fraction separated from streptomycin which was eluted with the buffer including 1% of sodium chloride. L was adsorb...