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PubMed1999

Intergenus protoplast fusion between Streptomyces and Micromonospora with reference to the distribution of parental characteristics in the fusants.

The protoplasts of two strains of Micromonospora which were sensitive to kanamycin (KM(s)) and utilized raffinose (Raf+), and one strain of Streptomyces griseus which was resistant to KM (KM(r)) and did not utilize raffinose (Raf-), were prepared, mixed in the presence of polyethylene glycol (PEG) and incubated on regeneration agar plates. Recombinant colonies showing KM(r)*Raf+ were obtained at a frequency of 2 x 10(-6). Their recombinants displayed a significant exchange of taxonomic characteristics between the two genera, although the majority appeared similar to the parent Micromonospora in their morphology as well as growth at 40 degrees C. Their patterns of utilization of carbohydrates, amino acids and diammonium hydrogenphosphate were different from those of the Micromonospora. Intermediate or novel types which different from their parents in their tolerance to NaCl and sensitivity to aminoglycoside antibiotics were also observed. Out of the 31 fusants obtained, two showed antimicrobial activity against Bacillus subtilis PCI 219, without any activity against Escherichia coli K-12 or Candida albicans 3147. The active substance may be a newly formed antibiotic, different from streptomycin in S. griseus.

Journal Article↗
PubMedDate not supplied

Characterization of a temperate actinophage, MPphiWR-1, capable of infecting Micromonospora purpurea ATCC 15835.

A temperate actinophage was isolated from soil using the gentamicin-producing microorganism, Micromonospora purpurea ATCC 15835 as host. The characterization of the phage represents the initial step in its development as a cloning vector. The phage isolated, MPphiWR-1, formed red- to purple-pigmented turbid plaques. Cells isolated from these plaques were resistant to superinfection with lytic mutants of MPphiWR-1. Southern blots of genomic DNA from a resistant culture showed that MPphiWR-1 integrated into the host genome. The phage was UV- or Mitomycin C-inducible. The integration, resistance to superinfection and inducibility indicated a lysogenic relationship with the host. Using MPphiE-RCPM, a lytic derivative, the phage host range was demonstrated to include members of three genera: one species each of Ampullariella and Catellatospora, and 12 species of Micromonospora. The phage belonged to Ackerman's B1 morphotype having an isometric head and a flexible noncontractile tail. The density of the phage was 1.525 g/cc. Restriction site mapping demonstrated that the phage DNA was 57.9 kb long and had cohesive ends. Using EDTA enrichment, viable mutants with deletions of at least 3.5 kb were isolated and mapped. Phage adsorption, sensitivities and plating efficiency were investigated. Non-liposome PEG-mediated transfection was demonstrated.

Adsorption↗
PubMed1978

Production of gentamicins by Micromonospora purpurea.

The natural medium contained the following ingredients (g/l): glucose 8.0, or black strap molasses (treated with 0.2--0.3 g/l EDTA) 12.0, fodder yeast (50.0% total nitrogen) 2.0, or folder yeast (40.0% total nitrogen) 6.0, or yeast extract 8.0, or tryptone 8.0, and CaCO3 1.0. Treated black strap molasses with EDTA and fodder yeast proved to be effective in the fermentative production of gentamicins. The most suitable chelating agent was EDTA in the form of disodium for the treatment of Komombo molasses in a concentration of 0.2--0.3 g/l, while potassium ferrocyanide and methylene blue had depressing effects on the production of gentamicins. The most effective carbon source, present in Egyptian black strap molasses, was glucose. Addition of glucose to the medium was preferable at the beginning of the fermentation process. Trace elements present in molasses were very essential for the microbial growth and biosynthesis of gentamicins as proved when molasses ash was added to the natural medium. Organic nitrogen sources were more suitable than inorganic nitrogen sources for the production of gentamicins by Micromonospora purpurea. The microorganism utilized the synthetic medium, but the antibiotic yields were less than those produced in the natural medium. The synthetic medium exhibited stimulatory effects of certain amino acids, organic acids, vitamins, and purine and pyrimidine bases on the fermentative production of gentamicins. Therefore, the ingredients increasing yields of gentamicins were mainly phenylalanine, iso-leucine, lysine, methionine, leucine, arginine, glycine, beta-alanine, cystine, tryptophan, malic acid, maleic acid, cobalamin, folic acid, riboflavin, vitamin B1, vitamin B6, biotin, nicotinamide, uracil, adenine, guanine, and adenosine. Trace elements (Co, Mo, Fe, Cu, Zn, and Mn) exhibited their important role on the biosynthesis and production of gentamicins by Micromonospora purpurea.

Carbon↗
PubMed1998

Analysis of plasmid pMZ1 from Micromonospora zionensis.

Plasmid pMZ1, isolated from Micromonospora zionensis, was also able to replicate by the rolling circle mechanism in Micromonospora melanosporea and Streptomyces lividans. Southern hybridisation experiments with probe prepared from pMZ1 and immobilised M. zionesis DNA fragments separated on pulsed-field gel electrophoresis, indicated that the plasmid is present in the progenitor strain in both integrated and autonomous states. Thiostrepton resistant derivatives of pMZ1 plasmid, pMZS25 and pMZS34, were used to study conjugal transfer in M. melanosporea and S. lividans. A 3.4 kb NcoI-MluI fragment from pMZ1 cloned in pIJ702 (plasmid pIJNM3) was shown to be sufficient to promote plasmid transfer and pock formation in S. lividans.

Blotting, Southern↗
PubMed1982

Ribosomal resistance in the gentamicin producer organism Micromonospora purpurea.

The mechanism of resistance of the gentamicin-producing organism Micromonospora purpurea was analyzed. Determination of minimal inhibitory concentrations revealed high resistance to the 4,6-substituted deoxystreptamine aminoglycosides amikacin, gentamicin, kanamycin, netilmicin, sisomicin, and tobramycin and also to lividomycin A and hygromycin B, but susceptibility to streptomycin, dihydrostreptomycin, paromomycin, and neomycin during all phases of the growth cycle. The nonproducing, closely related Micromonospora melanosporea was susceptible to these compounds. In agreement with results from previous studies (R. Benveniste and J. Davies, Proc. Natl. Acad. Sci. U.S.A. 70:2276-2280, 1973), extracts from M. purpurea showed no activity of enzymes specifically modifying gentamicin. 70S ribosomes from M. purpurea but not from M. melanosporea were resistant to inhibition by gentamicin, kanamycin, tobramycin, and lividomycin in a polyuridylic acid-dependent polyphenylalanine synthesis system and susceptible to those compounds which were inhibitory in vivo. The former antibiotics were also unable to induce misreading. Subunit exchange experiments between M. purpurea and M. melanosporea showed that the main site for inhibition and induction of misreading is the 30S subunit (up to gentamicin concentrations of 10 micrograms/ml).

Aminoglycosides↗
PubMed1976

A new actinomycin complex produced by a Micromonospora species: fermentation, isolation, and characterization.

A species of Micromonospora, Micromonospora floridensis NRRL 8020, has been found to produce an actinomycin complex consisting of at least 25 active components. After solvent extraction of the complex, separation of the individual components was carried out by preparative thin-layer chromatography. Hydrolysis and subsequent electrophoretic and chromatographic identification of the amino acid content of each of the isolated components have shown differences from known actinomycins, and the probability exists that these contain a number of amino or imino acids not previously found in other members of this group of antibiotics.

Amino Acids↗
PubMed1992

Cloning and characterization of an aminoglycoside resistance determinant from Micromonospora zionensis.

The sisomicin-gentamicin resistance methylase (sgm) gene was isolated from Micromonospora zionensis and cloned in Streptomyces lividans. The sgm gene was expressed in Micromonospora melanosporea, where its own promoter was active, and also in Escherichia coli under the control of the lacZ promoter. The complete nucleotide sequence of 1,122 bp and a transcription start point were determined. The sequence contains an open reading frame that encodes a polypeptide of 274 amino acids. The methylation of 30S ribosomal subunits by Sgm methylase accounts adequately for all known resistance characteristics of M. zionensis, but expression of high-level resistance to hygromycin B is background dependent. A comparison of the amino acid sequence of the predicted Sgm protein with the deduced amino acid sequences for the 16S rRNA methylases showed extensive similarity of Grm and significant similarity to KgmB but not to KamB methylase.

Amino Acid Sequence↗
PubMed1975

Fine structure of sporogenesis and septum formation in Micromonospora globosa Kriss and M. fusca Jensen.

Sporogenesis in two species of Micromonospora M. globosa and M. fusca (Actinomycetes) was quite similar. As in fungi, spore formation began as a blowing-out of a hyphal tip with the subsequent centripetal invagination of the plasma membrane. Septal wall material was deposited in a typical three-layered pattern, i.e., two electron-opaque layers separated by an electron-transparent layer. A second electron-opaque wall layer was later formed within the spore and finally a third, less electron-opaque wall was produced. Spore dihiscence was facilitated by the fragmentation of the first-formed wall surrounding the spore. Sporogenesis in Micromonospora is blastic in nature producing terminal, thick-walled spores. In M. fusca, a sporulation process was observed which closely resembled sporangial formation. The process appeared similar to that described for the genus Actinoplanes. Swollen, multiseptate structures were also present. Also in M. fusca, perforate septa with flared pore margins were observed. These septa were similar in appearance to the dolipore septa of Basidiomycetes although they lack a parenthesome and pore plug. Although an extensive membrane system (mesosome) was associated with the finishing septum, its function in the process of septum formation was not determined.

Cell Membrane↗
PubMed1975

The gentamicin antibiotics. 6. Gentamicin C2b, an aminoglycoside antibiotic produced by Micromonospora purpurea mutant JI-33.

A mutant strain of Micromonospora purpurea, designated var. JI-33, produced an antibiotic complex consisting primarily of gentamicin C1a. A further product of this fermentation was identical to a very minor component isolated from the fermentation of the parent organism and named gentamicin C2b. Physical measurements indicated its structure to be 6'-N-methylgentamicin C1a and this was confirmed by synthesis from gentamicin C1a. The in vitro antibacterial activity of gentamicin C2b was very similar to that of the gentamicin C complex. Antibiotic XK-62-2, produced by Micromonospora sagamiensis, appears to be identical to gentamicin C1b.

Chemical Phenomena↗
PubMed1976

A new broad spectrum aminoglycoside antibiotic, G-52, produced by Micromonospora zionensis.

G-52 is a new broad spectrum aminoglycoside produced by a species of the genus Micromonospora, Micromonospora zionensis. It has been differentiated from other known related antibiotics by a variety of chemical and biological methods. Its in vitro and in vivo spectrum of activity appears to be quite similar to that of verdamicin and gentamicin but is differentiated from them by its increased activity against 6'-N-acetylating strains.

Animals↗
PubMed1977

Macrolide antibiotics M-4365 produced by Micromonospora. I. Taxonomy, production, isolation, characterization and properties.

A series of basic 16-membered macrolide antibiotics, M-4365 A1, A2, A3, G1, G2 and G3, were isolated from the culture broth of strain MCRL 0940 which is assigned to be a new species of Micromonospora and for which the name Micromonospora capillata sp. nov. is proposed. Among these antibiotics, M-4365 A2 and G2 showed strong inhibitory activity against Gram-positive and Gram-negative bacteria.

Aminoglycosides↗
PubMed1980

New anthracycline glycosides from Micromonospora. I. Description of the producing strain.

During the course of successive mutagenic treatments of Streptomyces peucetius var. caesius, producer of anthracyclines, a novel mutant was isolated from a plate of the surviving population. This mutant showed remarkable morphological, cultural and biochemical differences when compared to the original strain. The new culture produced four new glycosides of a novel class within the group of the daunorubicin related anthracyclines, two of which were also present in the original strain. To our surprise the taxonomical study carried out on this mutant allowed its assignment to the genus Micromonospora ORSKOVA (1923). The possibilities of whether this new strain has originated from a contamination or from a mutation are discussed. The type strain is Micromonospora sp. strain B211 F.I. (identical to ATCC 31366; DSM 1190; FRI 4363).

Antibiotics, Antineoplastic↗
PubMed1990

Cloning and characterization of the sisomicin-resistance gene from Micromonospora inyoensis.

We cloned DNA fragments of sisomicin-producing Micromonospora inyoensis into Streptomyces plasmid vectors and identified Streptomyces lividans TK24 transformants expressing the M. inyoensis sisomicin-resistance (sisA) gene. The sisA gene was compared to the previously reported Micromonospora purpurea Kan-Gen (kanamycin-gentamicin)-resistance gene. While the restriction endonuclease digestion patterns of the two determinants appear to be divergent, the genes are nonetheless closely related, based on similar patterns and levels of aminoglycoside-resistance and their ability to cross-hybridize under stringent conditions. We have transformed recombinant plasmid pMD5-2, which carries the sisA gene, into our M. purpurea gentamicin-production strain and determined that gentamicin biosynthesis was not improved.

Blotting, Southern↗
PubMedDate not supplied

[Actinomycetes of the genus Micromonospora in meadow ecosystems].

Investigations showed that micromonosporas, along with streptomycetes, are the major inhabitants of floodplain meadow ecosystems, where their population varies from tens of thousands to hundreds of thousands of CFU per g substrate. In spring, the population of micromonosporas in soil and on the plant roots was found to be denser than that of streptomycetes.

Actinomycetales↗
PubMedDate not supplied

[Grouping of Micromonospora based on their cultural-morphologic features, antibiotic-sensitivity and formation of antibiotics].

500 Micromonospora cultures were subdivided into nine groups on the basis of their cultural-morphological properties, the ability to produce antibiotics of certain chemical classes, and the sensitivity to 18 different antibiotics: aurantiaca (I), cinnamomea (II), cinnamomea-vinacea (III), cinnamomea-olivacea (IV), nigra (V), nigra-violacea (VI), lilacinescens (VII), coerulea (VIII) and brunnea (IX). Cultures belonging to groups I, II, III, V and VI are moderately sensitive to most of the antibiotics and often occur in natural substrates. Black Micromonospora cultures (groups V and VI) mostly produce aminoglycoside antibiotics while brown cultures (groups II and III) form macrolide antibiotics. Cultures belonging to groups IV, VII, VIII and IX have a higher sensitivity to most of the antibiotics and are rarely isolated from natural substrates. These cultures have a weak ability to produce antibiotics.

Anti-Bacterial Agents↗
PubMed1985

[Inhibitor of aminoglycoside phosphotransferases from Micromonospora sp.--a producer of sisomicin].

A substance inhibiting the activity of aminoglycoside-3-'-phosphotransferases of both the actinomycetous and the bacterial origin was detected in the filtrates of the culture fluid and mycelium of Micromonospora sp. producing sisomicin. The activity of the substance against the aminoglycoside inactivating enzymes of different types was studied. It was shown that the quantity of the inhibitor in the culture fluid of Micromonospora sp. correlated with intensity of sisomocin production. Under conditions not providing production of the antibiotic the inhibitory activity was lacking. The inhibitor was purified by ion exchange chromatography on Amberlite CG-50 and KM-cellulose (NH+4 form), gel filtration through Sefadex G-50 and preparative paper chromatography. Stability of the inhibitor at different pH values and different temperatures, its sensitivity to certain enzymes and behaviour in high voltage electrophoresis were studied. The results of ultrafiltration showed that the molecular weight of the inhibitor was relatively low: less than 1000 D.

Chromatography, Gel↗