SEARCH · PubMed Health

Results for “bacterial filamentation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2000

The filamentous bacterial morphotype 'Nostocoida limicola' I contains at least two previously described genera in the low G+C gram positive bacteria.

Isolates of eight bacterial filaments fitting the published morphological description of 'Nostocoida limicola' I were obtained from the mixed liquor of four different Australian and one Czech Republic activated sludge plants by micromanipulation. On the basis of their near complete (Ben 200 and Ben 201), or partial (Ben 77, Ben 78, Ben 202, Ben 203, Ben 204 and Ben 205) 16S rRNA gene sequences, six of these isolates were 99.3-100% similar to Lactosphaera pasteurii and Trichococcus flocculiformis, a bulking filament only reported previously in Germany. The other two (Ben 203 and Ben 204) were 99.9% similar to Streptococcus suis. Hence, all are in the low mol % G+C gram-positive bacteria division of the Bacteria. On this evidence 'N. limicola' I is phylogenetically unrelated to 'Nostocoida limicola' II, which is now known to be in the Actinobacteria, even though these two filamentous bacteria appearing in activated sludge systems have been considered to be closely related to each other historically.

Actinobacteria↗

PubMed1976

Structure and assembly of filamentous bacterial viruses.

Filamentous bacterial viruses are flexible nucleoprotein rods, about 6 nm in diameter by 1000-2000 nm in length (depending on the virus strain). A protein shell encloses a central core of single-stranded circular DNA. The coat protein subunits forming the shell are largely alpha-helix, elongated in an axial direction, and also sloping radially, so as to overlap each other and give an arrangement of subunits reminiscent of scales on a fish. This arrangement of alpha-helices is rather like some models of myosin filaments. An early step in assembly of the virion is the formation of a complex between the viral DNA and an intracellular packaging protein that is not found in completed virions. Newly synthesized coat protein becomes associated with the plasma membrane of the cell. During the final steps of assembly, the packaging protein is displaced from the DNA and replaced by coat protein as the virion passes out through the plasma membrane of the host cell.

Bacteriophages↗

PubMed1979

Macromolecular structural transitions in Pf1 filamentous bacterial virus.

The filamentous bacterial virus Pf1 is a simple model for biological filaments. We have studied the structure of the virion and report here that the helix parameters of Pf1 change sharply with temperature at about 8 degrees C. Local interactions between protein subunits change by only a few tenths of an angstrom, but the changes are amplified between one end and the other of the virion to a rotation of 15 turns and a translation of 1,000 A. The limited nature of the phase transition is probably due to the constraints of 'knobs-into-holes' interaction between side chains of adjacent alpha-helical protein subunits. Treatment of the virion with ether causes a rearrangement of protein subunits into sheets, with the alpha-helices normal to the plane of the sheet. This phase transition suggests a model for virion assembly in the bacterial membrane.

Bacteriophages↗

PubMed1981

Structure of the protein and DNA in fd filamentous bacterial virus.

The virion of filamentous bacterial viruses comprises a cylindrical protein shell of o.d. approximately 60 A and i.d. 20A, containing a single-stranded circular DNA molecule which has two oppositely directed but not base-paired strands extending the length of the virion. The assembly of the virion involves an intracellular prepackaging of the DNA with a viral DNA-binding protein which is then displaced by the coat protein as the growing virion crosses the bacterial membrane. Studies of the virion by X-ray fibre diffraction show that the protein coat consists largely of alpha-helices oriented roughly parallel to the axis of the virion. As the normal to a planar peptide tends to align normal to a magnetic field, it is possible to improve significantly the orientation of virions in fibres using a strong magnet. The success of this technique with the Pf1 strain of virus led us to apply it to the better-known fd (f1, M13) strain. We report here new information about the arrangement of protein and DNA in the fd virion obtained from the improved diffraction pattern (Fig. 1).

Bacteriophages↗

PubMed2004

Early phase process scale-up challenges for fungal and filamentous bacterial cultures.

Culture pelleting and morphology has a strong influence on process productivity and success for fungal and filamentous bacterial cultures. This impact is particularly evident with early phase secondary metabolite processes with limited process definition. A compilation of factors affecting filamentous or pelleting morphology described in the literature indicates potential leads for developing process-specific control methodologies. An evaluation of the factors mediating citric acid production is one example of an industrially important application of these techniques. For five model fungal and filamentous bacterial processes in an industrial fermentation pilot plant, process development strategies were developed and effectively implemented with the goal of achieving reasonable fermentation titers early in the process development cycle. Examples of approaches included the use of additives to minimize pelleting in inoculum shake flasks, the use of large-volume frozen bagged inoculum obtained from agitated seed fermentors, and variations in production medium composition and fermentor operating conditions. Results were evaluated with respect to productivity of desired secondary metabolites as well as process scalability. On-line measurements were utilized to indirectly evaluate the cultivation impact of changes in medium and process development. Key laboratory to pilot plant scale-up issues also were identified and often addressed in subsequent cultivations.

Bacteria↗

PubMed1997

Bacterial filamentation of Yersinia pestis by beta-lactam antibiotics in experimentally infected mice.

OBJECTIVE: To identify alternatives to streptomycin for treating pneumonic plague, we evaluated beta-lactam antibiotics to treat experimental pneumonic plague in mice. METHODS: Mice were exposed to a lethal inhaled dose of Yersinia pestis and treated with beta-lactam antibiotics administered every 6 hours, starting 42 hours postexposure. RESULTS: The mice died or were euthanized in extremis 3 days postexposure. We observed marked bacterial filamentation of Y pestis in the tissues of mice treated with ceftazidime (10/10 mice), aztreonam (9/10 mice), or ampicillin (1/10 mice), but not in the tissues of mice treated with cefotetan, cefazolin, ceftriaxone, or saline. There was no evidence of septation of the filamentous bacteria by light or electron microscopy. The filamentous bacteria were confirmed as Y pestis based on their reactivity with rabbit anti-Y pestis F1 serum. CONCLUSIONS: Marked bacterial filamentation of Y pestis can be produced in vivo by certain beta-lactam antibiotics. This antibiotic-induced morphologic change is important because filamentous bacteria in clinical samples could possibly be confused with filamentous actinomycotic organisms.

Animals↗

PubMed2002

Filamentous bacterial population dominance in activated sludges subject to stresses.

Evolution of a filamentous bacterial population was monitored on four wastewater treatment pilot plants subject to stresses which have consisted of oxygen deficiencies and/or loading shocks. Fluorescent in situ hybridization (FISH) was used to perform filaments identification and quantification. Results obtained on the different pilot plants have led us to conclude that independently of the nature of the stresses, a single filamentous bacteria species was involved in the increase of the sludge volume index associated to the filamentous growth. In addition, when serial stresses were used, substitutions in dominant filamentous populations occurred: if another filament began to proliferate it caused the regression of the one which was formerly dominant.

Bacteria↗

PubMed1969

Fatty acids and polar lipids of extremely thermophilic filamentous bacterial masses from two Yellowstone hot springs.

The fatty acid composition of filamentous bacterial masses from two very hot Yellowstone Park springs is not unusual despite the extreme environment. Both populations have a series of C(14) to C(20) straight-chain acids with a maximum at C(18), and a series of saturated iso acids with a maximum at C(17) in one case and C(19) in the other. The fatty acid pattern of this anomalous group of organisms is like that of bacteria but not of blue-green algae. Both populations have similar polar lipids and identical carotenoids. It is speculated that these organisms may be adapted to their high-temperature environment by means of stable lipoprotein membrane systems.

Bacteria↗

PubMed2000

At-line monitoring of a submerged filamentous bacterial cultivation using near-infrared spectroscopy.

The use of near infra-red spectroscopy (NIRS) to monitor a submerged filamentous bacterial bioprocess was investigated. An industrial strain of the filamentous bacterium Streptomyces fradiae was cultured in a 12 litre stirred tank reactor (STR) using a complex medium. This mycelial 4 phase (oil, water, gas and solid) system produced highly complex and variable matrices, therefore monitoring such a complex fluid with NIRS represented a considerable challenge. Nevertheless, successful models for four key analytes (methyl oleate, glucose, glutamate and ammonium) were built at-line (rapid off-line) using NIRS. In the present study, the methods used to formulate, select and validate the models for the key analytes are discussed, with particular emphasis on how the model performance can be critically evaluated. Since previous reports on NIRS in monitoring bioprocesses have either involved simpler matrices, or, in filamentous systems, have not discussed how NIRS models can be critically assessed, the emphasis in the present study on providing an insight into the modelling process in such a complex matrix, may be particularly important to the applicability of NIRS to such industrial bioprocesses.

Journal Article↗

PubMed1981

Conformational transitions in Pf3 and their implications for the structure and assembly of filamentous bacterial viruses.

Laser Raman and circular dichroism spectra of filamentous bacteriophage Pf3 show that its coat protein is predominantly alpha-helical, similar to the subunits of bacteriophages Pf1 and fd. Unlike Pf1 and fd, however, the subunits of Pf3 are converted to beta-sheet structures by raising the temperature, the transition temperature depending upon phage and NaCl concentrations. On cooling, the beta structure reverts to an alpha structure the same as or similar to the native structure. On further heating it converts irreversibly to a second alpha-helical form different from the original one. The spectra also show that aromatic amino acid residues of Pf3 undergo dramatic changes in molecular environment during the alpha leads to beta transition. Similar transitions are observed to take place in the filamentous bacteriophage Xf.

Bacteriophages↗

PubMed2001

Phylogenetic characterization of the blue filamentous bacterial community from an Icelandic geothermal spring.

Molecular phylogenetic analysis of a blue filamentous community from an alkaline thermal spring (79-83 degrees C) in Iceland revealed that the blue filaments were affiliated with the Aquificales. The dominant sequence type, pIce1, was most closely related to a sequence (SRI-48) found in a white filamentous community from a separate Icelandic thermal spring and the pink filaments (EM17) from Yellowstone National Park. Fluorescent in situ hybridization with clone-specific oligonucleotide probes showed that the sample analyzed was essentially a monoculture of a single phylotype.

Journal Article↗

PubMed2001

Influence of transient substrate overloads on the proliferation of filamentous bacterial populations in an activated sludge pilot plant.

Using oligonucleotide probes directed at the rRNA of filamentous bacteria, this study looks at the influence of the components of transient substrate overloads on the growth of the dominant filamentous bacteria of activated sludge fed by a synthetic substrate. By dissociating the massive input of organic matter from the oxygen shortage that the latter generally induces, it is revealed that each of these factors applied alone, induces only transitory, small-scale growth of the filaments Nostocoida limicola, Haliscomenobacter hydrossis. Thiothrix and of type 021N. In contrast, combining them during a reconstituted transient substrate overload with an artificially created oxygen deficit, induces very fast growth of H. hydrossis which is responsible for establishing major proliferation. This massive proliferation was easily reduced by chlorination.

Bacteria↗

PubMed1999

Bacterial filament formation, a defense mechanism against flagellate grazing, is growth rate controlled in bacteria of different phyla.

A facultatively filamentous bacterium was isolated from eutrophic lake water and was identified as Flectobacillus sp. strain MWH38 (a member of the Cytophaga-Flavobacterium-Bacteroides phylum) by comparative 16S rRNA gene sequence analysis. Filament formation by Flectobacillus sp. strain MWH38 and filament formation by Flectobacillus major, the closest known relative of strain MWH38, were studied in chemostat cultures under grazing pressure by the bacterivorous flagellate Ochromonas sp. strain DS and without predation at several growth rates. The results clearly demonstrated that filament formation by the two flectobacilli is growth rate controlled and thus independent of the presence of a predator. However, flagellate grazing positively influenced bacterial growth rates by decreasing bacterial biomass and thus indirectly stimulated filament formation. The results of investigations of cell elongation and filament formation by Comamonas acidovorans PX54 (a member of the beta subclass of the class Proteobacteria) supported the recent proposal that in this species the mechanism of filament formation is growth rate controlled. The finding that the grazing defense mechanism consisting of filament formation is growth rate controlled in the flectobacilli investigated and C. acidovorans PX54 (i.e., in bacteria belonging to divergent evolutionary phyla) may indicate that this mechanism is a phylogenetically widely distributed defense strategy against grazing.

Animals↗

PubMed2006

The in situ physiology of "Nostocoida limicola" II, a filamentous bacterial morphotype in bulking activated sludge, using fluorescence in situ hybridization and microautoradiography.

The in situ physiology of the actinobacterial bulking and foaming filamentous bacterium "Nostocoida limicola" II was studied by fluorescence in situ hybridization/microautoradiography. Substrate assimilation patterns of pure cultures of this bacterium were different to those seen in activated sludge biomass samples. There was no evidence to suggest that "N. limicola" II preferred hydrophobic substrates, but evidence was produced to support the view that it is metabolically active under anaerobic conditions in activated sludge.

Actinobacteria↗

PubMed2001

Design and application of oligonucleotide probes for fluorescent in situ identification of the filamentous bacterial morphotype Nostocoida limicola in activated sludge.

16S rRNA targeted probes, designed using sequence data from pure cultures of the three morphotypes of the filamentous bulking bacteria Nostocoida limicola I, II and III and their successful application to the in situ identification of these bacteria in activated sludge biomass samples are described here. Two probes were required to detect all the sequenced N. limicola II isolates. Results from fluorescent in situ hybridization suggest that the morphotypes N. limicola I and II contain at least two phylogenetically unrelated bacteria. The N. limicola II filaments that did not respond to the probes designed in this study fluoresced instead with the probes previously designed for the alpha-Proteobacteria. The data also suggest that both N. limicola I and III can exist in activated sludge as single, paired or clumped cells and thus in a form not recognizable microscopically as this morphotype. Some N. limicola II filaments which responded to the probes designed here were much thinner than the filaments conventionally 'identified' as this morphotype and better fitted the descriptions often used in the literature for N. limicola I.

Actinobacteria↗

PubMed1981

Primary structure of the major coat protein of the filamentous bacterial viruses, If1 and Ike.

The primary structures of the major coat proteins from If1 and Ike filmentous coliphages have been determined by automated Edman degradation before and after cyanogen bromide cleavage and by manual sequencing of certain tryptic peptides. Carboxypeptidase A and B digestion was also used to determine the sequence of the COOH termini of these proteins. A comparison of the major coat proteins from these two phages with those from other filamentous phages show that they all share several common features, namely an asymmetric distribution of positively and negatively charged amino acid residues, which are clustered with the COOH-terminal and NH2-terminal regions respectively, and a region of 19 residues which is located in the middle of the polypeptide chain. The consequences of this charge distribution for a possible mechanism of virus maturation are discussed.

Amino Acid Sequence↗

PubMed1981

Phage X: a plasmid-dependent, broad host range, filamentous bacterial virus.

Phage X was isolated from sewage as plating on Escherichia coli or Salmonella typhimurium strains harbouring the incompatibility group X plasmid R6K. It also plated on a strain of Serratia marcescens carrying this plasmid. It failed to form plaques on Proteus mirabilis, P. morganii or Providencia alcalifaciens harbouring R6K, but did multiply on them. No phage increase occurred with homologous R- strains. Phage X also plated or registered an increase in titre on E. coli or S. typhimurium strains carrying various plasmids of incompatibility groups M, N, P-1, U or W as well as the unassigned plasmid R775. It adsorbed to pili determined by a group P-10 plasmid in a Pseudomonas aeruginosa strain but did not multiply on this organism. The phage was filamentous and curly, resistant to ribonuclease and diethyl ether and sensitive to chloroform. It adsorbed to the tips of pili.

Adsorption↗

PubMed1995

C2, and unusual filamentous bacterial virus: protein sequence and conformation, DNA size and conformation, and nucleotide/subunit ratio.

Inovirus C2 is 1295 nm long and 6.8 nm in diameter, and its mass is 24 million Da. Its genome is a topologically circular, single-stranded DNA molecule of 8100 nucleotides. The DNA is packed in the virion as two antiparallel strands, with a rise per nucleotide in each strand of 3.2 A; it can be assigned spectroscopic properties like those of base-stacked, right-handed, double-stranded DNA. The stoichiometric ratio (n/s) of nucleotides to subunits of the major coat protein is close to 2. The protein subunit contains 52 amino acids, and the DNA sequence of its gene does not encode a signal peptide. The protein conformation in the virion is helical, mostly alpha-helix with perhaps some 3(10)-helix. The amino acid sequence of the DNA interaction domain of the subunit is unique among Inovirus species. On the basis of its coat protein sequence and available theories of helical symmetry in such structures, C2 appears to be either an unusual member of filamentous virus symmetry class II or the defining member of a new symmetry class.

Amino Acid Sequence↗