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PubMed2005

Force and flexibility of flailing myxobacteria.

Myxococcus xanthus is a common Gram-negative bacterium that moves by a process called gliding motility. In myxobacteria, two distinct mechanisms for gliding have been discovered. S-type motility requires the extension, attachment, and retraction of type IV pili. The other mechanism, designated as A-type motility, may be driven by the secretion and swelling of slime; however, experiments to confirm or refute this model are still lacking and the force exerted by this mechanism has not been measured. A previously published experiment found that when an M. xanthus cell became stuck at one end, the cell underwent flailing motions. Based on this experiment, I propose an elastic model that can estimate the force produced by the A-motility engine and the bending modulus of a single myxobacterial cell. The model estimates a bending modulus of 3 x 10(-14) erg cm and a force between 50-150 pN. This force is comparable to that predicted by slime extrusion, and the bending modulus is 30-fold smaller than that measured in Bacillus subtilis. This model suggests experiments that can further quantify this process.

Cell Adhesion↗
PubMed1987

Control of morphogenesis in myxobacteria.

The myxobacteria are Gram-negative soil bacteria that live in large communities known as swarms. The most remarkable characteristic of myxobacteria is their ability to form fruiting bodies that have a species-specific shape and color. Fruiting body formation requires the concerted effort of hundreds of thousands of cells. Development is initiated only when two conditions are satisfied. The cells must be nutritionally deprived (environmental signal) and there must be many other cells in the vicinity (intercellular signal). The development of one species, Myxococcus xanthus, has been studied in the most detail. M. xanthus uses amino acids as its primary carbon, nitrogen, and energy source. Starvation for a single amino acid, or for inorganic phosphate, serves as the environmental signal. A variety of intercellular signals appear to control the initiation of development and the timing of subsequent developmental events.

Cloning, Molecular↗
PubMed1985

The corallopyronins, new inhibitors of bacterial RNA synthesis from Myxobacteria.

From the culture broth of the myxobacterium, Corallococcus (Myxococcus) coralloides, three new antibiotics have been isolated: corallopyronin A, B and C. The compounds, which are chemically related to the recently discovered myxopyronins, act mainly on Gram-positive bacteria, with MIC values between 0.1 and 10 micrograms/ml, and only exceptionally or at much higher concentrations (MIC values; 100 and more micrograms/ml) on Gram-negatives. They do not inhibit eukaryotic organisms and show no toxicity for mice (sc). The corallopyronins appear to block specifically eubacterial RNA polymerase.

Animals↗
PubMed1988

Novel macrocyclic antibiotics: megovalicins A, B, C, D, G and H. I. Screening of antibiotics-producing myxobacteria and production of megovalicins.

New antibiotics belonging to macrocyclic were discovered and named megovalicins A, B, C, D, G and H. The antibiotics were accumulated endogeneously by a newly isolated myxobacterium identified as Myxococcus flavescens. Tank culture of the bacterium for 4 days gave 8.8 g cells/liter on a wet basis, and 4.8, 7.1, 20.0, 0.4, 3.75 and 15.0 micrograms of megovalicins A, B, C, D, G and H respectively were obtained from 1 g wet cells.

Anti-Bacterial Agents↗
PubMed1988

Saframycin Mx1, a new natural saframycin isolated from a myxobacterium.

A new natural saframycin was discovered in the culture broth of the myxobacterium, Myxococcus xanthus strain Mx x48. The fermentation and isolation of the antibiotic are described. The name, saframycin Mx1, is proposed. The compound appears to interact with cellular DNA.

Anti-Bacterial Agents↗
PubMed1999

Melithiazols, new beta-methoxyacrylate inhibitors of the respiratory chain isolated from myxobacteria. Production, isolation, physico-chemical and biological properties.

New antibiotic compounds, melithiazols, were isolated from the culture broth of strains of the myxobacteria Melittangium lichenicola, Archangium gephyra, and Myxococcus stipitatus. The compounds belong to the group of beta-methoxyacrylate (MOA) inhibitors and are related to the myxothiazols. The melithiazols show high antifungal activity, but are less toxic than myxothiazol A and its methyl ester in a growth inhibition assay with mouse cell cultures. The melithiazols inhibit NADH oxidation by submitochondrial particles from beef heart. Melithiazol A blocks the electron transport within the bc1-segment (complex III) and causes a red shift in the reduced spectrum of cytochrome b.

Acrylates↗
PubMed2000

Evolution of viruses by acquisition of cellular RNA or DNA nucleotide sequences and genes: an introduction.

The origins of virus evolution may be traced to Archeabacteria since Inouye and Inouye (6) discovered a retroelement with a gene for reverse transcriptase in the bacterial genome and in the satellite, multiple copy single stranded DNA (msDNA) in the soil bacterium Myxococcus xanthus. It was possible (8) to define the evolution of retroelements in eukaryotic cells of plants, insects (gypsy retrovirus) and vertebrates. The replication of RNA viruses in eukaryotic cells allowed for the viral RNA genome to integrate a cellular ubiquitin mRNA, as reported for BVDV (24). Another example is the integration of 28S ribosomal RNA into the hemagglutinin gene of an influenza virus. This change in the hemagglutinin gene led to an increased pathogenicity of the influenza virus (25). In contrast to RNA viruses, DNA viruses had evolved by inserting cDNA molecules derived from mRNA transcripts of cellular genes or foreign viral RNA. It is of interest that the virus acquired cellular genes in the genomes of DNA viruses represent genes that code for proteins that inhibit cellular molecular processes related to HLA class I and II molecules. The other acquired genes are cellular genes that code for cytokines that are capable of inhibiting antigen presentation to T cells by antigen presenting cells (APC) by dendritic Langerhans cells. The acquisition of cellular genes by DNA viruses enhances their pathogenicity by inhibiting the hosts' defense systems.

Animals↗
PubMedDate not supplied

[Effect of various storage methods on the viability of myxobacteria].

Viability of myxobacteria strains Myxococcus xanthus UNCM 10041, Polyangium cellulosum UNCM 10043, Archangium gephyra UNCM 10001 stored by the methods of lyophilization, cryoconservation, drying on paper discs, suspending in distilled water or physiological solution under a layer of mineral oil. The best results on viability preservation of all three studied strains were obtained when using the method of cryoconservation. It has been shown that the strains M. xanthus and A. gephyra preserve the best viability during two years of observations when stored in liquid nitrogen and dried on paper discs. Strain P. cellulosum preserves viability for two years when stored in liquid nitrogen and in suspensions on distilled water and physiological solution.

Bacteriological Techniques↗
PubMed1975

[Investigations on the structure of the sphingolipids of the genus Bacteroides (author's transl)].

In 1972 Fritsche and Thelen have described the difference between the structure of the komplex lipids of the genus Bacteroides and the genus Sphaerophorus. Further investigations of Fritsche demonstrated the possibility of grouping gramnegative anaerobes into the genus Bacteroides in spite of the fact, that one of the final products of metabolism of these strains is butyric acid. These strains are the so-called butyric acid producing Bacteroides. This paper describes the structure of the still unknown fatty acids of the komplex lipids of Bacteroides strains and confirms the heterogenity of the sphingosine bases of Bacteroides as a principle. Fife strains of Bacteroides - with and without production of butyric acid - were used for purification of their long chain bases, which were characterized by degradation. The unknown fatty acids were isolated from B. thetaiotaomicron and analyzed by Dr. Rosenfelder with the aid of mass spectrometry, O-methylation and dehydratisation. The experiments of Rosenfelder demonstrate, that the unknown fatty acids have the behaviour of 3-hydroxy fatty acids, the two main peaks are a hexadecanoic and a heptade-behaviour of 3-hydroxy fatty acids, the two main peaks are a hexadecanoic and a heptadecanoic acid. They have an identical behaviour with the 3-hydroxy-15-methyl-palmitic acid of Myxococcus fulvus. Therefore the genus Bacteroides differs from the genus Sphaerophorus by synthesis of 3-hydroxy fatty acids. The production of sphingolipids is a common characteristic of the genus Bacteroides, each of the five strains demonstrated a heterogeneous pattern of bases with sphingosines with 16 to 20, perhaps also 12 to 14 carbon atoms, sometimes predominantly the branched and n-heptadeca- and the octadeca-sphinganine can be identified. The possibility of the production of phyto-sphingosines is discussed.

Bacteroides↗
PubMed1979

[Aquatic myxobacteria (Sporocytophaga cauliformis) and the order "Myxobacterales" (author's transl)].

The indicator function of aquatic myxobacteria for the purpose of evaluating drinking water quality as well as their occurrence in sewage effluent make it desirable to describe these hitherto little known organisms in more detail. To this end, a comparative investigation of anaerobic myxobacteria of the genus Sphaerocytophaga, two typical representatives of the Order Myxobacterales (Myxococcus fulvus, Sporocytophage cauliformis), and a strain ov Vitrepscilla (Vitroescilla proteolytica) was undertaken. With respect to culture morphology, the migratory fringe surrounding colonies of Sphaerocytophaga similar to the other strains studies was a prominent characteristic. In particular, the similarity with colonies of Sporocytophaga cauliformis was apparent. The gliding motility typical of Sphaerocytophaga could be demonstrated in all of the strains investigated. Scanning electron micrographs revealed an amorphous layer of slime covering the cell surfaces in all strains compared in this study, thus excluding the existence of more rigid organelles of locomotion. Taxonomically, the anaerobec myxobacteria of the oral cavity (Sphaerocytophaga) belong to the Order "Myxobacterales" and not the "Eubacterales", i.e., to the genus Fusobacterium. This is clearly suggested by their motility lacking flagella and, above all, by their cell morphology which differs from the Eubacterales.

Culture Media↗
PubMed2000

[Isolation and identification of myxobacteria].

This paper reported that the authors isolated large numbers of myxobacteria from more than 100 samples collected in many places of China. More than 400 pure strains were obtained. These strains belonged to 10 genera of Myxococcales. The most frequent genera isolated were Myxococcus, Sorangium, Corallococcus, and Cystobacter. Melittangium was seldom isolated. No Chondromyces and Haploangium were found.

Cellulose↗
PubMedDate not supplied

[Effect of UV-radiation and drying on bacterium diversity in soil].

It has been shown that after DNA-injuring factors (UV irradiation or drying) action on soil one could observe the decrease of the total quantity of bacteria and the number of species, i.e., the decrease of microbe diversity. At the same time not numerous species were found in soils after their action. Thus the drying or UV-irradiation makes it possible to estimate more completely the microbe diversity in soils as well as to find resistant bacteria. It has been established that the strain Methylobacterium extorquens, M. mesophilicum, Bacillus subtilis, B. cereus, which were isolated after UV irradiation or drying of oil samples, were characterized by high resistance to gamma-irradiation (LD99.99--5-10 kGr). Bacteria (representatives of Pseudomonas genus) sensitive to drying or UV-irradiation were also sensitive to ionizing radiation (LD99.99--0.09 kGr). Nocardieforms and representatives of Myxococcus occupied intermediate position between representatives of genera Methylobacterium and Pseudomonas as to resistance to the above-mentioned stress agents.

Bacteria↗
PubMedDate not supplied

[Monitoring of microbial degraders in manned space stations].

Samples of microorganisms from the surface of constructions of Mir Space Station (Mir SS) were taken and examined after 13 years of operation. The following microorganisms were isolated and identified: 12 fungal species belonging to the genera Penicillium, Aspergillus, Cladosporium, and Aureobasidium; 3 yeast species belonging to the genera Debaryomyces, Candida, and Rhodotorula; and 4 bacterial species belonging to the genera Bacillus, Myxococcus, and Rhodococcus. The predominant species in all samples was Penicillium chrisogenum. It was shown that the fungi isolated could damage polymers and induce corrosion of aluminum-magnesium alloys. We commenced a study of microbial degraders on constructions of the Russian section of the International Space Station (RS ISS). Twenty-six species of fungi, bacteria, yeasts, and actinomycetes, known as active biodegraders, were identified in three sample sets taken at intervals. We founded a collection of microorganisms surviving throughout space flights. This collection can be used to test spacecraft production materials, in order to determine their resistance to biodegradation.

Bacteria↗
PubMed1981

Binding properties of myxobacterial hemagglutinin.

The nature of the receptor for myxobacterial hemagglutinin (MBHA) on the outer surface of Myxococcus xanthus was investigated by studying the binding of 125I-MBHA to vegetative and developmental cells. The amount of binding and hence the number of binding sites/cell appeared to increase 4-fold during development to 2.1 X 10(4) sites/cell. Furthermore, the apparent association constant (Ka) for MBHA increased 3-fold to 3 X 10(7) M-1. Fetuin, a glycoprotein which binds MBHA, blocked the binding of 125I-MBHA to vegetative cells but not developmental cells. Thus, the MBHA binding sites from developmental cells clearly differ from the vegetative binding sites. The Ka for MBHA binding to sheep erythrocytes (3.5 X 10(6) M-1) was an order of magnitude lower than that of developmental M. xanthus cells. The erythrocyte binding sites are also much more sensitive to concanavalin A inhibition than the M. xanthus sites.

Animals↗
PubMed1984

An inhibitor of mitochondrial respiration which binds to cytochrome b and displaces quinone from the iron-sulfur protein of the cytochrome bc1 complex.

Myxothiazol, an antibiotic from Myxococcus fulvus, which inhibits mitochondrial respiration in the bc1 complex of the respiratory chain, has effects on the redox components of isolated succinate-cytochrome c reductase complex which suggest that it interacts with both cytochrome b and the iron-sulfur protein of the bc1 complex. The inhibitor appears to increase the midpoint potentials of cytochromes b-562 and b-566, as indicated by an increase in their reducibility by the succinate/fumarate couple. It also causes a red shift in the optical spectrum of ferrocytochrome b-566, as reported previously (Becker, W. F., Von Jagow , G., Anke , T., Steglisch , W. (1981) FEBS Lett. 132, 329-333). This red shift is enhanced by Triton X-100, and there is no shift in the spectrum of b-562. These results are consistent with evidence that mutations conferring myxothiazol resistance in yeast map to the mitochondrial gene for cytochrome b ( Thierbach , G., and Michaelis, G. (1982) Mol. Gen. Genet. 186, 501-506). In addition, myxothiazol has effects on reduction of the cytochromes b and c1 by succinate or ubiquinol which are identical to those caused by removal of the iron-sulfur protein from the bc1 complex. It blocks reduction of cytochrome c1 during single and multiple turnovers of the bc1 complex, but does not block reduction of the b cytochromes. In the presence of antimycin, it blocks reduction of both cytochromes b and c1. In contrast to antimycin, myxothiazol inhibits oxidant-induced reduction of both b cytochromes and does not inhibit their oxidation by fumarate. Myxothiazol also inhibits reduction of the iron-sulfur protein by ubiquinol and shifts the gx resonance in the EPR spectrum of the iron-sulfur protein from g = 1.79 to 1.76. It does not affect the midpoint potential of the iron-sulfur protein, but does eliminate the increase in midpoint potential which is caused by inhibitory hydroxyquinones which bind to the iron-sulfur protein. The effects of myxothiazol are consistent with a protonmotive Q cycle pathway of electron transfer in which myxothiazol binds to cytochrome b and displaces quinone from the iron-sulfur protein of the bc1 complex. These results suggest either that a myxothiazol-induced conformational change in cytochrome b is transmitted to a quinone binding site on the iron-sulfur protein, or that there is a quinone binding site which consists of peptide domains from both cytochrome b and iron-sulfur protein.

Animals↗
PubMed1981

[Myxobacteria (Myxobacteriales) on leaf surfaces].

140 leaf samples were examined, 73 of which (= 52.1%) contained myxobacteria. Three species of the genus Myxococcus, M. virescens, M. fulvus and M. coralloides, could be found more or less frequently in the phyllosphere of woody plants and annuals. Archangium gephyra was observed only once. There was no significant difference in the occurrence of myxobacteria between evergreen leaves and leaves from deciduous trees and shrubs. Fruit-trees yielded the best results.

Myxococcales↗
PubMed1994

PIM1 encodes a mitochondrial ATP-dependent protease that is required for mitochondrial function in the yeast Saccharomyces cerevisiae.

The PIM1 nuclear gene in the yeast Saccharomyces cerevisiae encodes a mitochondrial ATP-dependent protease that exhibits over 30% identity with ATP-dependent protease La from Escherichia coli, Lon from Bacillus brevis, and one from Myxococcus xanthus. In addition, Pim1 is 1133 amino acids long and has a putative mitochondrial import signal in the N-terminal region. Enzymatic comparisons of normal PIM1+ and deficient pim1-delta strains revealed that the ATP-dependent protease is located within the mitochondrial matrix. The pim1-delta strains are unable to utilize nonfermentable substrates as the sole carbon source and are unable to maintain functional mitochondrial DNA, indicating that the Pim1 protease is required for mitochondrial function. PIM1 mRNA is constitutively expressed but is increased after thermal stress, suggesting that Pim1 may play a role in the heat shock response.

ATP-Dependent Proteases↗