SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Blocked mutants of Micromonospora echinospora defective in the production of the potent antitumor agent calicheamicin are described. Analysis of intermediates produced by blocked mutants indicates a branched biosynthetic pathway. Mutants that produced some, but not all, calicheamicin forms are also described.
Mouldy hay was produced in the laboratory by sterilising good hay, inoculating with aqueous suspensions of microorganisms, and incubating at 40 degrees or 60 degrees C. Extracts were tested for presence of farmer's lung hay (F.L.H.) antigen by agar-gel double-diffusion and immunoelectrophoresis tests against sixteen to twenty sera from patients with farmer's lung. F.L.H. antigen developed in hay after: (1) inoculating with mixed microbial suspensions from antigenically active hay; (2) inoculation with mixed suspensions of pure cultures of thermophilic actinomycetes, after raising the pH of the hay to 70 either by prior inoculation with fungi or by infiltration with ammonia vapour; and (3) inoculation at pH 70 with pure cultures of Thermopolyspora polyspora or with Micromonospora vulgaris. F.L.H. antigen did not develop in hay after inoculation with fungi only, or with six other actinomycetes tested, or after prior heating (though some sera reacted to fungal antigens in all these extracts). T. polyspora is the richest source yet found of F.L.H. antigen, and inhalation of an extract by affected subjects produces some of the features of farmer's lung. Pure cultures can produce F.L.H. antigen on artificial media without hay. Spores and mycelium are rich in F.L.H. antigen, and inhalation of the spores may play a part in farmer's lung disease. Other antigens relevant to farmer's lung may be found in other actinomycetes, not yet cultured.
M-GTFI, an inhibitor of glucosyltransferase from S. mutans was produced by Micromonospora narashinoensis strain No. 731. The isolation procedure for M-GTFI was improved and established for spectroscopic analyses, and some properties of the inhibitor were investigated. The structure of M-GTFI was shown to be trisodium [2-sulphonato-(E)-9-undecenyll-oxacyclotriacont-(E)-3- en-2-one, 16, 18-bis sulphonate. The chemical structure of M-GTFI was therefore similar to that of izumenolide which is a beta-lactamase inhibitor containing sulfate ester groups in its molecule. The inhibitory characteristics of M-GTFI were parallel to that of other inhibitory compounds containing sulphate esters but the spectrum of activity was wider.
New inhibitors of DNA topoisomerase named 2280-DTI and 2890-DTI have been discovered in the culture filtrates of Micromonospora sp. strain No. 2280 and Streptomyces sp. strain No. 2890, respectively. Both inhibitors were purified from each culture filtrate by column chromatography on Diaion, Dowex and gel filtration. Both inhibitors were thermostable acidic substances with high molecular weight and inhibited topoisomerase I in a non-competitive manner. They differed from well-known inhibitors of topoisomerases such as camptothecin and doxorubicin, which inhibit the DNA rejoining reaction of the enzyme by intercalation into DNA strands or stabilizing the cleavable complex (enzyme-DNA reaction intermediate). 2280-DTI and 2890-DTI did not intercalate into DNA strands and also had no ability to stabilize the cleavable complex. It is suggested that 2280-DTI and 2890-DTI inhibit the DNA breaking and rejoining reactions of topoisomerase by direct action on the enzyme molecule.
Sisomicin, a new aminoglycoside antibiotic which is produced by Micromonospora myoensis, was studied against 565 clinical isolates of gram-negative bacilli and gram-positive cocci. With the exception of Serratia marcescens, over 90% of isolates of gram-negative bacilli were inhibited by 1.56 mug/ml or less of sisomicin. Sisomicin was slightly more active than gentamicin and tobramycin aganist isolates of Escherichia coli, Proteus mirabilis and Klebsiella spp. It was substantially more active than butirosin and kanamycin against all gram-negative bacilli. Isolates of gram-negative bacilli which were resistant to gentamicin and tobramycin were also resistant to sisomicin. Most of these isolates were sensitive to amikacin.
Cultures of Micromonospora species, strains MK 65 and MK 62, were found to produce a new antibiotic XK-62-2 (Sagamicin). Antibacterial and paperchromatographic data on an eluate from IRC50 treatment of fermentation beers indicated that XK62-2 is a new antibiotic with broad spectrum, basic, and water-soluble properties, probably closely related to the gentamicin C group of antibiotics.
Utilizing a mutant of Micromonospora inyoensis which requires the addition of 2-deoxystreptamine for sisomicin production, the bioconversion of 2-deoxstreptamine containing pseudodisaccharides and pseudotrisaccharides into sisomicin was demonstrated. The trisaccharides tested were structurally related minor components found in the sisomicin or gentamicin fermentations. Based upon the specificity of the structural configuration of those compounds which were converted to sisomicin versus those which were not, a pathway for the biosynthesis of sisomicin is proposed.
Utilizing a paromamine-producing mutant of Micromonospora purpurea blocked in the production of gentamicin, bioconversion of various minor gentamicin components into the gentamicin C complex was demonstrated. The compounds tested were structurally related to the gentamicin C's and are found as minor components in the gentamicin fermentation. Based upon the bioconversions detected, a branched pathway for the biosynthesis of the gentamicin C components is proposed.
A culture of Micromonospora species MK-70 was found to produce two new antibiotics, fortimicins A and B. Antibacterial and paper chromatographic data on an eluate from IRC-50 treatment of fermentation beers indicated that fortimicins A and B are new antibiotics with broad-spectrum, basic and water-soluble properties. Fortimicin A exhibited potent, unique, broad-spectrum antibacterial activity against Gram-positive and negative bacteria both in vitro and in vivo, while fortimicin B was only weakly active.
The aminoglycoside antibiotics fortimicins A and B produced by a naturally occurring strain Micromonospora sp. MK-70 were isolated from its fermentation beer. Fortimicins A and B were isolated as water-soluble, basic, white amorphous powders having molecular formula C17H35N5O6 and C15H32N4O5, respectively. Acid hydrolysis of fortimicin A indicated that it has one mole of glycine in its molecule while fortimicin B has not. Paper chromatography, silica-gel and carbon thin-layer chromatography revealed that fortimicins A and B are novel aminoglycoside antibiotics.
Sagamicin, an aminoglycoside antibiotic, was labeled with tritium by means of a platinum catalyzed hydrogen exchange reaction and by carbon-14 in two biosynthetic procedures. 14C-Methyl-L-methionine was used as the radioactive precursor in these biological processes involving Micromonospora sagamiensis. The distribution of radioactivity in 14C-sagamicin and gentamicin C1 was studied by mild acid hydrolysis and Hofmann degradation. The results showed that both C- and N-methyl groups were derived from methionine. One of the biosynthetic processes involved the conversion of gentamicin into sagamicin with resting cells and labeled methionine.
From the fermentation broth of Micromonospora olivoasterospora CS-26 that produced fortimicins A and B three new aminoglycoside antibiotics, fortimicins C, D and KE, were isolated. Fortimicins C and D exhibited potent, broad spectrum antibacterial activities against Gram-positive and negative bacteria, while fortimicin KE was only weakly active.
Mycinamicins, novel macrolide antibiotics were obtained from the culture broth of Micromonospora grisseorubida sp. nov. Isolation of five components, mycinamicins I, II, III, IV and V, was accomplished by silica gel adsorption or partition chromatography. Mycinsmicin I and II exhibit a strong UV absorption peak at 218 nm and have a shoulder at 240 nm. Mycinamicin III, IV and V show strong UV absorption peaks at 215 nm and around 280 nm. From their physicochemical and biological properties, the mycinamicins are classified as new macrolide antibiotics.
A novel antitumor antibiotic complex has been obtained from the culture broth of Actinomycete strain DO-11 (KY11091) isolated from a soil sample collected in Sendai, Miyagi, Japan. On the taxonomic studies the producing organism is described as Micromonospora chalcea KY11091. For the production of the antibiotics, soluble starch served as a good carbon source and yeast extract was the best nitrogen source tested. The antibiotic complex designated as tetrocarcins is active against Gram-positive bacteria, but is not active against Gram-negative bacteria. Tetrocarcin A showed bacteriocidal activity against Bacillus subtilis.
New components of tetrocarcins (E1, E2, F and F-1) were found in the culture broth of Micromonospora chalcea KY 11091 that was known to produce tetrocarcins A, B and C. Tetrocarcin F-1 consisted of tetronolide and nitro sugar (tetronitrose). Tetrocarcins E1 and E2 consisted of F-1 and deoxy sugar (L-digitoxose). Tetrocarcin F consisted of F-1 and two deoxy sugars (their structures were not yet determined). They all showed antibacterial activities against Gram-positive bacteria and the specific activity decreased with decrease in the numbers of deoxy sugars attached to the aglycone.
The hazimicins, a new class of broad spectrum antibiotics with at least 2 active components (5 and 6), were isolated from the fermentation of Micromonospora echinospora var challisensis SCC 1411. The complex was separated from the broth by a solvent extraction procedure, and the individual components were separated by column chromatography. The two primary active components are isomers, with unique structures shown to be di-tyrosine analogs containing two isonitrile groups. The antibiotic has in vitro activity against Gram-positive and Gram-negative bacteria, and in vitro activity against yeasts and dermatophytes.
A new antibiotic, dapiramicin, has been isolated from the fermentation broth of Micromonospora sp. SF-1917. Since the dapiramicin exhibited essentially no in vitro activity by usual bioassays, two assay methods for dapiramicin were developed, HPLC and a new bioassay by growth inhibition of fungal mycelia on a slide glass. Fermentation of dapiramicin is also described.
New nucleoside antibiotics, dapiramicins A and B produced by a Micromonospora sp. SF-1917, have been isolated by column chromatography on Diaion HP-20 and silica gel. Physico-chemical properties suggested that they are disaccharide nucleosides. Dapiramicin A underwent epimerization, under acidic condition, into epidapiramicin A. Although dapiramicin A generally exhibits no in vitro activity, it is very effective against the sheath blight of rice plants caused by Rhizoctonia solani in a green house test.