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At least 307 records · Page 17Linked to original sources
PubMed1978

[Dependence of the component makeup of the gentamicin complex on Micromonospora purpurea var. violacea 1935 cultivation conditions].

Dependence of biosynthesis of gentamicin and vitamin B12 on complex and "synthetic" media under conditions of decreased aeration, increased phosphorus levels and non-optimal content of carbon source was studied. The decreased levels of vitamin B12 production under conditions of the non-optimal content of the carbon source and increased phosphorus levels in the medium resulted in decreased production of the antibiotic complex as a whole and decreased relative content of the most methylated gentamicins C1 and C2 in the complex. Decreased aeration lowered the mycelium productivity with respect to the antibiotic production without changing the ratio of the components in the complex and the level of vitamin B12 production.

Aerobiosis↗
PubMed1980

[Optimization of the makeup of the fermentation nutrient medium for detecting antibiotic producers among Micromonospora].

An optimal fermentation medium for detection of antibiotic-producing cultures among Micromonosporaceae at the stage of primary screening was developed. The method of the experiment factor design with regard both for the qualitative and the quantitative variation of the medium composition was used. The number of the active strains detected with the use of medium M1 amounts to 76.4 per cent of the cultures tested. The same efficiency was observed with simultaneous use of 6 different fermentation media. The use of the new medium significantly decreases the labour-consuming character of the procedure.

Anti-Bacterial Agents↗
PubMed1974

Biological activity of antibiotic G-418, a new micromonospora-produced aminoglycoside with activity against protozoa and helminths.

On the basis of parallel in vitro studies with antibiotic G-418, gentamicin, neomycin, and kanamycin, antibiotic G-418 was found to be less potent than gentamicin but more active than either kanamycin or neomycin against most strains, with the exception of Pseudomonas, for which neomycin was more active than antibiotic G-418, and enterococci, for which antibiotic G-418 was more active than the other three antibiotics. Mouse protection tests indicated that antibiotic G-418 is approximately half as potent as gentamicin and its acute toxicity is one-half to one-third that of gentamicin.

Animals↗
PubMed1988

Neihumicin, a new cytotoxic antibiotic from Micromonospora neihuensis. III. Structure-activity relationships.

Structure-cytotoxicity relationships studies have indicated that the C-3 and C-6 disubstituted piperazine-2,5-diones are structurally required for significant cytotoxicity, and the neihumicin-like C-3 and C-6 disubstituted unsymmetrical piperazine derivatives are, in general, more cytotoxic than the corresponding symmetrical piperazine-2,5-diones. Several synthetic analogs including 3,6-di-(2,4,5-trimethoxybenzylidene)piperazine-2,5- dione, 3,6-dibenzylidene-2-ethoxy-3,6-dihydropyrazine-5-one, 3-benzylidene-6-(m-chlorobenzylidene)-2-methoxy-3,6-dihydropyrazine++ +-5-one, have been shown to be more cytotoxic than neihumicin.

Antibiotics, Antineoplastic↗
PubMed1979

[Methodological procedures for detecting antibiotic producers among cultures of the family Micromonosporaceae].

Data on intensification of the search for active cultures among Micromonospora are presented. It was shown that the frequency of detecting the antibiotic-producing cultures among Micromonospora under conditions of fermentation on the corn-glucose medium inoculated with agar blocks amounted to 35 per cent. The use of nutrient media of different composition for growing submerged inoculum of Micromonospora demonstrated that the rate of its growth reached maximum on the peastarch medium. The use of this medium for growing submerged seed material for fermentation in the corn-glucose medium increased the frequency of detecting active cultures from 35 to 43.1 per cent. The assay of Micromonospora antibiotic activity twice, i.e. in 96 and 240 hours of the fermentation process increased the frequency of detecting active cultures up to 57.1 per cent and revealing greater variety of antibiotics. Fermentation of Micromonospora cultures simultaneously on 6 different nutrient media inoculated with submerged seed mycelium and assay of the activity for 2 times, i. e. in 96 and 240 hours allowed a detection of up to 76.2 per cent of active strains out of the total number of the isolates.

Anti-Bacterial Agents↗
PubMed2006

Deciphering the biosynthesis pathway of the antitumor thiocoraline from a marine actinomycete and its expression in two streptomyces species.

Thiocoraline is a thiodepsipeptide antitumor compound produced by two actinomycetes Micromonospora sp. ACM2-092 and Micromonospora sp. ML1, isolated from two marine invertebrates (a soft coral and a mollusc) found of the Indian Ocean coast of Mozambique. By using oligoprimers derived from nonribosomal peptide synthetase (NRPS) consensus sequences, six PCR fragments containing putative NRPS adenylation domains were amplified from the chromosome of Micromonospora sp. ML1. Insertional inactivation of each adenylation domain showed that two of them generated nonproducing mutants, thereby indicating that these domains were involved in thiocoraline biosynthesis. Sequencing of a 64.6 kbp DNA region revealed the presence of 36 complete open reading frames (ORFs) and two incomplete ones. Heterologous expression of a region of about 53 kbp, containing 26 of the ORFs, in Streptomyces albus and S. lividans led to the production of thiocoraline in these streptomycetes. Surprisingly, the identified gene cluster contains more NRPS modules than expected on the basis of the number of amino acids of thiocoraline. TioR and TioS would most probably constitute the NRPS involved in the biosynthesis of the thiocoraline backbone, according to the colinearity of the respective modules. It is proposed that two other NRPSs, TioY and TioZ, could be responsible for the biosynthesis of a small peptide molecule which could be involved in regulation of the biosynthesis of thicoraline in Micromonospora sp. ML1. In addition, a pathway is proposed for the biosynthesis of the unusual starter unit, 3-hydroxy-quinaldic acid.

Animals↗
PubMed1981

[Directed screening of aminoglycoside antibiotic producers on selective media with gentamycin].

The method of directed screening of aminoglycoside antibiotics is based on the natural phenomenon that fresh isolates of Micromonospora are highly resistant to the antibiotics produced by them. The method consists of plating of the soil samples on selective media with gentamicin (10--25 micrograms/ml). The frequency of Micromonospora against the total number of the isolated actinomycetes increased from 3.3--11.4 to 30.6--78 per cent. The number of the cultures isolated from the control medium and active against gramnegative test-bacteria amounted to 13.4 per cent, while the number of Micromonospora isolated from the selective medium with gentamicin and active against gramnegative test-bacteria amounted to 69.4 per cent. 37 crude antibiotics were isolated with the method of ion exchange concentration usually used for aminoglycoside antibiotics. The new antibiotics were identified as 2-desoxy amine-containing aminoglycosides by cross resistance of aminoglycoside resistant strains of Staphylococci to them, the methods of paper and thin-layer chromatography and mass spectrometry. The majority of the aminoglycosides belonged to the gentamicin group. 2 compounds with molecular weights not described in the literature for aminoglycosides were isolated.

Aminoglycosides↗
PubMed1964

ANTIGENIC STRUCTURE OF THE ACTINOMYCETALES. VII. CHEMICAL AND SEROLOGICAL SIMILARITIES OF CELL WALLS FROM 100 ACTINOMYCETALES STRAINS.

Kwapinski, J. B. (The University of New England, Armidale, Australia). Antigenic structure of the Actinomycetales. VII. Chemical and serological similarities of cell walls from 100 Actinomycetales strains. J. Bacteriol. 88:1211-1219. 1964.-Cell walls prepared mechanically from 100 strains of Actinomycetales were studied by chromatographic and serological methods. The cell walls of Actinomyces were found to be serologically related to those of the corynebacteria and to some strains of mycobacteria and nocardiae. The cell walls of nocardiae appeared to be more closely related to those of the mycobacteria, Streptomyces, Micromonospora, and Waksmania. The cell walls of Micromonospora and Waksmania showed certain serological similarities to those of Thermoactinomyces and nocardiae. Micropolyspora was antigenically different from other species of the Actinomycetales. Three serological groups of mycobacteria and four groups of nocardiae were distinguished.

Actinomyces↗
PubMed1992

N-formimidoyl fortimicin A synthase, a unique oxidase involved in fortimicin A biosynthesis: purification, characterization and gene cloning.

Micromonospora olivasterospora, a fortimicin A (FTM A, astromicin) producer, was found to carry an enzyme that converts FTM A to N-formimidoyl FTM A (FI-FTM A). This enzyme (FI-FTMase) was purified to homogeneity and shown to be a flavin adenine dinucleotide (FAD) enzyme. Tracer experiments proved that the formimidoyl group was derived from C-2 of glycine via oxidation of the amino acid in the presence of FTM A and oxygen. The gene encoding this enzyme, fms 14, was cloned using a 26-mer oligonucleotide probe, designed according to the N-terminal amino acid sequence of purified FI-FTMase, from a cosmid clone pGLM990, which has been shown to contain a cluster of FTM A biosynthetic genes. The nucleotide sequence, and biochemical and genetic analysis revealed that FI-FTMase is composed of four identical subunits of mol. wt. 52,000, and contains at least one FAD per subunit. DNA regions homologous to fms14 were found in two other producers of the fortimicin group of antibiotics, Dactylosporangium matsuzakiense ATCC31570 and Micromonospora sp. SF-2098.

Actinomycetales↗