L-2-Amino-4-(2-aminoethoxy)-trans-3-butenoic acid was isolated from a fermentation broth of an unidentified species of Streptomyces, X-11, 085. This substance inhibited the growth of Streptomyces cellulosae in a chemically defined minimal medium. The growth inhibition was reversed noncompetitively by L-cysteine and competitively by L-lysine, L-arginine and L-ornithine.
We have isolated cultures of fungi from soil samples collected in southern China and are now reporting the incidence of antibiotic activities in 54 isolates which were identified as 30 species belonging to the order Moniliales of the class Fungi imperfecti. This study of non-predacious Moniliales freshly isolated from nature indicates a strikingly high incidence of antiprotozoally active substances in this order of microorganisms. These data are in good accordance with our earlier observations1) based on screening of predacious Moniliales from culture collections.
Actinomycete spores having various shapes and ornamentation were suspended in soil, and their removal by elution with water was examined. Spores of Streptomyces sp. strains SS-22, SS-28 and SS-254 isolated from shallow sea muds were rapidly removed. The precipitation of these spores in suspension with either distilled water or saline water was examined. Sodium chloride was found to accelerate the precipitation of most strains. The effect of temperature and salt concentration on actinomycete growth was examined and growth of most strains was found to be retarded by low temperature and high salt concentration. All strains survived under the test conditions, except Streptomyces aureofaciens. One strain of this species was unable to survive culturing in 3.5 % NaCl, for 10 days at 15°C.
Kanamycin inactivation enzyme from E. coli K12 ML1629 was partially purified and some properties were examined. The enzyme was very unstable under ultraviolet light, and was stabilized in the presence of -S-S- reductants.
Institute of New Antibiotics, Academy of Medical Sciences, Moscow, USSR In the course of our screening program we have isolated from the culture fo Actinomadura carminata carminomycin, a new anthracycline antibiotic which possessed strong antitumor activity in animal experiments. It is produced as a mixture of several active components: the more interesting ones are components 1, 2 and 3. Components 2 and 3 can be transformed by means of mild hydrolysis into carminomycin 1, which is obtained as a red crystalline hydrochloride C26H27O10N•HCl. The ultra-violet and visible spectra resemble that of daunomycin but are different.
A large number of strains of Alternaria kikuchiana that cause the black spot disease on pear were isolated from some orchards of Tottori Prefecture, Japan. From them seven strains, which showed different sensitivities to polyoxin B, were selected and used in the experiments. Polyoxin B, at a concentration of 10μM, inhibited more than 50% of the incorporation of glucosamine-14C into cell-wall chitin in washed mycelia of the polyoxin-sensitive strains and at the same time resulted in an unusually increased accumulation of UDP-N-acetylglucosamine-14C, which is a precursor of chitin biosynthesis. Both the inhibition of glucosamine-14C incorporation into chitin and the increase of accumulation of UDP-N-acetylglucosamine-14C caused by polyoxin B were moderately lowered with decreasing the sensitivity to the antibiotic of the different strains. Crude preparations of chitin synthetase were obtained from these strains. Polyoxin B strongly inhibited all the enzyme preparations in competition with their substrate UDP-N-acetyl-glucosamine. The Km values for the substrate or the Ki values for the antibiotic determined in the enzyme reactions differed slightly from each other. These results indicate that polyoxin B acts as an competitive inhibitor of chitin synthetase, which is concerned in the synthesis of cell-wall chitin of A. kikuchiana. And they also suggest that the polyoxin-resistance of this fungus is caused by a lowered penetration of the antibiotic through the cell membrane into the enzyme site.
Biosynthesis of pepstatin by Streptomyces testaceus HAMADA et OKAMI was studied.U-14C-L-Alanine and U-14C-L-valine were incorporated into alanine and valine moietiesof pepstatin respectively. U-14C-L-Leucine, U-14C-malonate and U-14C-acetate were incorporatedinto (3S, 4S)-4-amino-3-hydroxy-6-methylheptanoic acid (AHMHA) moiety of pepstatin. Radioactivity of U-14C-L-leucine was located almost exclusively in C3-C8 of AHMHA but not in C1 and C2 and radioactivity of U-14C-malonate was located in C1 and C2 Labeled AHMHA itself was not incorporated into pepstatin. Malonate was incorporated into pepstatin at about 18 times higher rate than acetate. These results indicate that AHMHA is biosynthesized from L-leucine and malonic acid during biosynthesis of pepstatin and suggested that pepstatin biosynthesis proceeds on a multienzyme system in a similar way as in the case of fatty acid synthesis.
Emerimicins II, III and IV are new antibiotics produced by Emericellopsis microspora when 4-traps-n-propyl-L-proline (propyl proline) is added in the fermentation medium. Emerimicins are similar to antiamoebin and stilbellin. However, all emerimicins have been differentiated from the latter antibiotics by comparison of tic behavior and aminoacid composition. Propyl proline appears to induce the production of the new antibiotics since the aminoacid was not incorporated into the molecules of emerimicins II, III, or IV.
A third naphthaquinone pigment isolated from Torula herbarin is now identified as O-methylherbarin by IR, NMR and mass spectroscopic methods. The structure is confirmed by partial synthesis by methylation of herbarin using methyl iodide and silver oxide. The gas chromatographic-mass spectrometric characteristics of herbarin, dehydroherbarin and O-methylherbarin are described.
The biosynthesis of lasalocid A (formerly antibiotic X-537 A) in cultures of Strepto-myces lasaliensis has been studied using 13C- and 14C-labelled precursors. The antibiotic is derived from five acetate, four propionate and three butyrate units. This study has provided the first illustration of an ethyl group arising from butyrate and 2-ethylmalonate.