Actinomycete metabolism; incorporation of 14C-labelled compounds into streptomycin

Radioactive Myoinositol: Incorporation into Streptomycin

Radioactive myoinositol was rapidly incorporated into streptomycin by Streptomyces griseus. All the incorporated radioactivity was found in the streptidine moiety of the antibiotic, as shown by chemical degradation of the streptomycin. To a certain extent inositol reversed the depressing effect of phosphate on the production of the antibiotic.

Secondary metabolite biosynthesis: the first century

An account of work on the biosynthesis of secondary metabolites up to 1965 is presented. The earliest suggestions for three of the four major pathways were speculative; for the isoprene rule, hypotheses date to 1877, for the polyketide rule to 1907, and for a role for amino acids in alkaloid biosynthesis to 1910. The fourth major pathway based on intermediates of the shikimic acid pathway has a much shorter history because shikimic acid itself was only identified as a primary metabolite in 1951. In addition to speculation, biomimetic syntheses were carried out in which chemists attempted to duplicate possible biosynthetic pathways in vitro. The classic example was Robinson's synthesis of tropinone in 1917. Direct examination of secondary metabolite biosynthesis was possible with the use of the isotopic tracer technique. This methodology, applied extensively to primary metabolism beginning in 1935 and to secondary metabolism from about 1950, was facilitated by the increasing availability of the 14C isotope. With the use of isotopes as tracers, the broad outlines of secondary metabolite biosynthesis, reviewed here, were established in the period 1950 to 1965.

Studies on the biosynthesis of streptomycin

Myo-inositol, especially in combination with arginine, enhances streptomycin production. Compounds which show structural relationship with myo-inositol are ineffective.Myo-inositol decreases the incorporation of C(14)-glucose into streptomycin, particularly into streptidine. This effect suggests that myo-inositol is a precursor of the streptidine ring. Methionine stimulates antibiotic production in a synthetic medium but proves to be unfavorable in a complex medium. The gamma- and delta-isomers of hexachlorocyclohexane inhibit streptomycin formation. The formation of streptomycin by washed mycelium was studied. Essentially the same results were here obtained as with growing cultures.

Myo-inositol in the biosynthesis of streptomycin by Streptomyces griseus

When myo-inositol is present in a growing culture of Streptomyces griseus the yield of streptomycin is increased, and the amount of carbon-14-from uniformly labeled glucose-incorporated into the streptidine and streptobiosamine moieties of streptomycin is lowered by 41 percent and 21.7 percent, respectively. These results present strong indirect evidence for the participation of myo-inositol or its metabolic products in streptidine biosynthesis.

Biosynthesis of N-methyl-L-glucosamine from D-glucose by Streptomyces griseus

Biosynthesis of N-methyl-L-glucosamine moiety of streptomycin from D-glucose by Streptomyces griseus was studied. A mixture of D-[1-(14) C] glucose and D-[6(-3)H]glucose was given to the culture of S. griseus. The 3H/14C ratio found in N-methyl-L-glucosamine further supports a mechanism that the conversion of D-glucose to L-hexose is carried out without scission of carbon skeleton. When D-[1-14C]glucose and D-[3-3H]glucose were used, the fall of 3H/14C ratio in N-metyl-L-glucosamine showed that the hydrogen atom at C-3 plays a rôle in such a transformation.

[Physiology and biochemistry of streptomycetes. III. Incorporation of D-glucose-u-14C in paramomycin as indicator of antibiotic biosynthesis by Streptomyces albus var. metamycinus nov. var]

Paromomycin was isolated from culture filtrates of Streptomyces albus var. metamycinus nov. var. after feeding the growing cultures with D-glucose-u-14C. From the different incorporation rates conclusions concerning different features of the paromomycin biosynthesis (utilization of the carbon source, proportional and disproportional changes of the rates of synthesis) could be drawn. Uptake and metabolism of glucose are discussed.

Fermentation studies with Streptomyces griseus. I. Carbohydrate sources for the production of protease and streptomycin

The effects of four carbon sources and inorganic phosphate on the production of streptomycin and protease by a strain of Streptomyces griseus were studied. Protease production was increased in fermentations with comparatively rapid consumption of carbohydrate, and streptomycin was produced under conditions of moderately slow consumption. Starch was consumed more rapidly than glucose, and, in fermentations with starch as a carbon source, good yields of protease were associated with poor yields of streptomycin. The effect of the concentration of inorganic phosphate varied with the sugar source; the rate of consumption of glucose or fructose increased with the addition of inorganic phosphate, and the utilization of starch or maltose was not affected.