A new antimicrobial agent, coumermycin**, has been isolated from fermentation beers of a strain of Streptomyces named Streptomyces rishiriensis nov. sp. The strain, No. 404Y3 in our culture collection, was isolated from a sample of soil collected in Rishiri Island, Hokkaido, Japan. The antibiotic is a white acidic substance and relates to novobiocin^7–13) in some respects of biological and chemical properties. The chromatographic and degradation studies on the antibiotic revealed the fact that the original culture produces several components which seemed to be closely related each other. Therefore, studies were undertaken to obtain a single component having the most potent biological activity which has been designated coumermycin A₁.

This paper deals with the producing organism, production, isolation as well as biological and physico-chemical properties of coumermycin A₁. The structural studies on coumermycin A₁, C₅₅H₅₉N₅O₂₀, will be reported in companion papers¹⁾.

A strain, Streptomyces sp. No. 69895, was isolated from a soil sample collected in Sikkim. The present authors found that strain produced two antibiotics, antibiotic 69895 A and B, simultaneously and identified them to be chromomycin^1,2,3,4) and oleandomycin⁵⁾, respectively. Up to now, St. griseus No. 7¹⁾ was reported as a chromomycins-producing strain and St. antibioticus ATCC 11891⁶⁾ as an oleandomycin-producing strain. On theother hand, many streptomyces strains producing antibiotics related to chromomycin or oleandomycin were reported. But the above-mentioned strain was found to differ from those producing chromomycin, oleandomycin or antibiotic related to them only, and a streptomyces strain which produce chromomycin and oleandomycin simultaneously has never reported.

The present paper deals with the mycological properties of Streptomyces sp. No. 69895, comparison of the properties of the strain with those of related streptomyces strains, extraction and purification procedure, and physicochemical properties of antibiotics 69895 A and B.

Two new polyhydroxy basic antibiotics have been isolated from a culture broth of a Streptomyces obtained from a soil sample collected in Yokohama, Japan, the major component named destomycin A and the minor one named destomycin B. The organism was characterized to form the aerial hyphae with secondary whorls and was assigned to a new species, Streptomyces rimofaciens by T. Niida in our laboratory.

Destomycins A and B are broad antimicrobial epectrum antibiotics, especially active against some kinds of fungi. Destomycin A is more active against Mycobacteria than destomycin B.

In the present publication, the production, isolation and characterization of destomycins are described.

Under the generic name of “quinoxaline antibiotic”, six antibiotics are known, i.e. quinomycins A, Band C, and triostins A, Band C. In 1961, when Katagari and Sugiura¹⁾ tested the effect of quinomycins A, B and C, and triostin complex on 34 transplantable tumors in the mouse, rat, hamster and chicken, they noticed the selective activity of quinomycin A on rat tumors and of quinomycin C as well as triostin complex on mouse tumors. Quinomycin B was inactive in a practical sense. Thus these antibiotics, though related in chemical structure, can be said not to be related as far as their antitumor activities are concerned.

This kind of biological specificity of the quinoxaline antibiotics also holds true with the bacterial resistance to the antibiotic. No or little cross-resistance was observed with the Staphylococcus aureus strains resistant to quinomycins A, C and triostin C²⁾.

In an effort to establish the selective activity of respective compound more clearly, two ascites type tumors, Ehlrich carcinoma in mice and ascites hepatoma AH-130 in rats, were treated with quinomycins A,C and triostin C, and total packed cell volume (TPCV) was examined to evaluate the effect in a quantitative manner. These results will be reported in this communication.

A Streptomyces, No. 3668-L2, isolated from a soil sample taken from the campus of University of Tokyo produced an antibiotic which had properties similar to bottromycin discovered by Waisvisz et at¹. Acid hydrolysis of bottromycin have been known to yield valine, glycine, β-methylphenylalanine, β-2-thiazole-β-alanine and two unidentified ninhydrin-positive substances^{2, 3, 4)}. The similar amino acids and ninhydrin-positive substances were isolated from the hydrolysate of the antibiotic No. 3668-L2 and the two ninhydrin-positive substances were determined to be β,β-dimethyl-α-aminobutyric acid (DMAB) and ʟ-cis-3-methylproline. In another paper, the structural studies of the antibiotic No. 3668-L2 which was identified as bottromycin will be reported by Nakamura et al⁵⁾. Besides the amino acids described above, a small amount of ʟ-proline was isolated from a hydrolyzate of the antibiotic No. 3668-L2, and it suggested an existence of a small amount of another antibiotic. Actually, the antibiotic No. 3668-L2 was shown by a thinlayer chromatography to contain the main component which was identical with bottromycin and designated bottromycin A, and another minor component designated bottromycin B. Bottromycins A and B were separated and bottromycin B was suggested to have a similar structure to bottromycin A except L-proline moiety instead of ʟ-cis-3-methylproline. This paper presents characteristics of Streptomyces No. 3668-L2, isolation and properties of bottromycins A and B.

Several workers have isolated various antimicrobial compounds from cultures of B. subtilis. Of these compounds some were isolated as liquids^1~4), others as crystalline^5~10), while amorphous antimicrobial agents could also be separated^11~24). Most of these antimicrobial agents have polypeptide nature which on hydrolysis give positive ninhydrin test^1~24).

Through the present communication, isolation of antimicrobial agent and its characteristics are described.