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Query: UNIPROT:Q96DG6 (Pseudomonas)
 76,258 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The structure and distribution of extracellular polymer surrounding Bacillus circulans, Diplococcus (Streptococcus) pneumoniae, Streptococcus salivarius, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Herella vaginacola (Acinetobacter calcoaceticus), and Agrobacterium tumefaciens were studied by electron microscopy. A modified ruthenium red staining procedure was used to examine the fine structure of capsule and slime. Freeze-etching and critical-point drying were used to examine the quantity of unaltered exocellular material. Comparative data demonstrate that fibrillar extracellular polymer surrounding B. circulans, D. pneumoniae, and K. pneumoniae is capsule (cell wall attached) which is characteristic of the producing organism. Capsular polymer generally appeared fibrillar, although globular polymer consisted of capsular subunits bound to S. salivarius and H. vaginacola. Exocellular slime was present about S. aureus, P. aeruginosa, and A. tumefaciens.
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PMID:Fine structure and distribution of extracellular polymer surrounding selected aerobic bacteria. 4 74

Upon exposure to 6,000 U of polymyxin B sulfate per ml, cells of the polymyxin-sensitive PAO 1 strain of Pseudomonas aeruginosa displayed in thin sections long projections arising from the outer membrane of the cell wall and extensive cytoplasmic degradation with accumulation of cytoplasmic membrane infoldings. Polymyxin-resistant isolates derived from the PAO 1 strain, however, grew well in the presence of 6,000 U of polymyxin per ml and exhibited none of these effects, having instead the appearance of a typically healthy cell. Freeze-etching of cells of the sensitive strain grown in basal medium without polymyxin revealed a concave cell wall layer studded with numerous particles. Freeze-etching of cells of the resistant isolates grown in basal medium containing 6,000 U of polymyxin per ml revealed a concave cell wall layer (i.e., the outer half of the outer membrane) in which most of these particles were absent. Thus, acquisition of resistance to polymyxin was correlated with an alteration in the architecture of the outer membrane. When the resistant isolates were grown in the basal medium lacking polymyxin and then freeze-etched, the particle distribution in the concave cell wall layer resembled that of the sensitive parent strain. The cells had regained sensitivity to polymyxin upon suspension in medium containing 6,000 U/ml as determined by their failure to grow and by internal damages seen in thin sections. These cells also had acquired increased sensitivity to ethylenediaminetetraacetate, whereas the polymyxin-resistant cells grown in the presence of polymyxin were resistant to lysis by ethylenediaminetetraacetate. The polymyxin-resistant isolates were not stable mutants but instead represented an adaptive response to the presence of polymyxin in the medium.
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PMID:Ultrastructural study of polymyxin-resistant isolates of Pseudomonas aeruginosa. 17 6

A replica plating method for rapid quantitation of ice nucleation-active (INA) bacteria was developed. Leaf washings of plant samples from California, Colorado, Florida, Louisiana, and Wisconsin were tested for the presence of INA bacteria. Of the 95 plant species sampled, 74 were found to harbor INA bacteria. Only the conifers were, as a group, unlikely to harbor INA bacteria. All of the INA bacteria isolated resembled either Pseudomonas syringae or Erwinia herbicola. Sufficient numbers of INA bacteria were present on the samples to account for the ice nuclei associated with leaves that are necessary for freezing injury to occur. Numbers of INA bacteria were large enough to suggest that plant surfaces may constitute a significant source of atmospheric ice nuclei.
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PMID:Distribution of ice nucleation-active bacteria on plants in nature. 73 41

Samples of aerosol from the surrounding air were collected by forcing them to impact onto a solid nutrient medium, onto membrane filters, or onto microscope slides on microcover slips. The samples were cultivated or viewed in a fluorescence microscope by using a technique developed by us, or investigated by scanning electron microscopy. The amounts of microorganisms found by cultivation method, i.e. those forming microcolonies (CFU), were on average 85% lower than the amounts determined by the fluorescence technique. Cultivation of microorganisms trapped on Synpor filters of various pore size resulted in lower counts than conventional cultivation. Among bacteria, the genera Micrococcus, Bacillus and Corynebacterium predominated; the genera Neisseria, Actinomyces, Pseudomonas and others were also found. Of micromycetes, the genera Penicillium, Aspergillus and Cladosporium occurred most frequently in air. In the summer season, yeasts and other micromycetes prevailed, whereas in the winter season the bacteria counts were higher. The total counts of all components of the aeroplankton were higher in summer than in winter. Dust particles bounded mainly bacteria.
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PMID:Airborne microorganism monitoring: a comparison of several methods, including a new direct counting technique. 195 Feb

Freeze-substitution was performed on strains of Escherichia coli, Pasteurella multocida, Campylobacter fetus, Vibrio cholerae, Pseudomonas aeruginosa, Pseudomonas putida, Aeromonas salmonicida, Proteus mirabilis, Haemophilus pleuropneumoniae, Caulobacter crescentus, and Leptothrix discophora with a substitution medium composed of 2% osmium tetroxide and 2% uranyl acetate in anhydrous acetone. A thick periplasmic gel ranging from 10.6 to 14.3 nm in width was displayed in E. coli K-12, K30, and His 1 (a K-12 derivative containing the K30 capsule genes), P. multocida, C. fetus, P. putida, A. salmonicida, H. pleuropneumoniae, and P. mirabilis. The other bacteria possessed translucent periplasms in which a thinner peptidoglycan layer was seen. Capsular polysaccharide, evident as electron-dense fibers radiating outward perpendicular to the cell surface, was observed on E. coli K30 and His 1 and P. mirabilis cells. A more random arrangement of fibers forming a netlike structure was apparent surrounding cells of H. pleuropneumoniae. For the first time a capsule, distinct from the sheath, was observed on L. discophora. In all instances, capsular polysaccharide was visualized in the absence of stabilizing agents such as homologous antisera or ruthenium red. Other distinct envelope structures were observed external to the outer membrane including the sheath of L. discophora and the S layers of A. salmonicida A450 and C. crescentus CB15A. We believe that the freeze-substitution technique presents a more accurate image of the structural organization of these cells and that it has revealed complex ultrastructural relationships between cell envelope constituents previously difficult to visualize by more conventional means of preparation.
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PMID:Freeze-substitution of gram-negative eubacteria: general cell morphology and envelope profiles. 199 83

Essential oil of clove, dispersed (0.4% v/v) in a concentrated sugar solution, had a marked germicidal effect against various bacteria and Candida albicans. Staphylococcus aureus (five strains), Klebsiella pneumoniae, Pseudomonas aeruginosa, Clostridium perfringens, and Escherichia coli inoculated at a level of 10(7) cfu/ml, and C. albicans (inoculum 4.0 x 10(5) cfu/ml) were killed (greater than 99.999%) after 2-7 min in a laboratory broth supplemented with 63% (v/w) of sugar, and containing 0.4% (v/w) of essential oil of clove. Added organic matter (i.e. human or bovine serum) did not impair its antimicrobial activity. Sugar was not necessary for the antimicrobial activity of clove oil, but the concentrated sugar solution provided a good vehicle for obtaining an oil dispersion that is relatively stable for certain practical applications.
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PMID:Antimicrobial activity of clove oil dispersed in a concentrated sugar solution. 254 13

The adhesion of Pseudomonas aeruginosa strain 492c to trypsinized and untrypsinized buccal epithelial cells (BECs) was studied. Kinetic analysis of the adhesion data, employing a Langmuir absorption isotherm, indicated the presence of two classes of binding sites on untrypsinized BECs: a high affinity - low copy number site (apparent association constant (Ka) approximately equal to 1.57 X 10(-8) mL/cell with ca. 29 binding sites/cell) and a low affinity - high copy number class of binding sites (Ka approximately equal to 4.78 X 10(-10) mL/cell with ca. 264 binding sites/cell). The low affinity - high copy number class of sites was found to be trypsin sensitive. A single class of binding sites was found on trypsinized BECs exhibiting a high affinity - low copy number (Ka approximately equal to 3.70 X 10(-7) mL/cell with ca. 31 binding sites/cell). Positive cooperativity in binding of P. aeruginosa strain 492c to the low affinity - high copy number class site on untrypsinized BECs was demonstrated by analysis of Hill plots of the adhesion data. Sugar inhibition data using a preincubation methodology showed an inhibition of adhesion to trypsinized BECs in the presence of N-acetylneuraminic acid and D-arabinose, while these same two sugars enhanced adhesion to untrypsinized BECs. D-Galactose and N-acetylglucosamine enhanced adhesion to both types of BECs though the latter did to different extents. D-Fucose only inhibited adhesion to untrypsinized BECs.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adhesion of Pseudomonas aeruginosa to human buccal epithelial cells: evidence for two classes of receptors. 286 82

The binding of outer membrane (OM) ghosts derived from Pseudomonas aeruginosa strain 492c to human buccal epithelial cells (BECs) was examined. Electron microscopic examination of the binding of OM ghosts to BECs revealed direct OM ghost-BEC interaction. Equilibrium analysis of the binding of OM ghosts to trypsinized BECs employing the Langmuir adsorption isotherm indicated the number of binding sites (N) to be 1.3 X 10(-4) micrograms protein per BEC with an apparent association constant (Ka) of 3.4 X 10(-2) mL/microgram protein. The Langmuir analysis of binding of OM ghosts to untrypsinized BECs was complex, suggesting two possible classes of receptors, a high affinity-low copy number class (Ka, 7.8 X 10(-2)mL/microgram protein; N, 8.6 X 10(-5) microgram protein per BEC) and a low affinity-high copy number class (Ka, 3.7 X 10(-3)mL/microgram protein; N, 9.2 X 10(-4)microgram protein per BEC). Sugar inhibition studies incorporating D-galactose enhanced binding to each BEC type. N-Acetylneuraminic acid and N-acetylglucosamine both enhanced binding of OM ghosts to untrypsinized BECs, while inhibiting binding to trypsinized BECs. D-Arabinose inhibited binding to both BEC types. Binding of OM ghosts to both BEC types was greatly inhibited by D-fucose, while L-fucose only greatly inhibited binding to untrypsinized BECs. These sugar inhibition data demonstrated a difference in the binding of OM ghosts to trypsinized and untrypsinized BECs and possibly reveal the nature of the receptor(s), free of possible bacterial metabolic effects.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The binding of Pseudomonas aeruginosa outer membrane ghosts to human buccal epithelial cells. 308 53

Amikacin, an aminoglycoside known to inhibit protein synthesis, was found to perturb the outer membrane of a sensitive Pseudomonas aeruginosa strain (ATCC 9027). This perturbation was monitored using electron microscopy and biochemical analyses. Following exposure to 20 micrograms amikacin/mL for 15 min, the outer membrane of exponentially growing cells lost 15% of its protein, 18% of its lipopolysaccharide, and 18% of its phosphate. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that the whole spectrum of outer membrane protein and lipopolysaccharide was affected. Similarly, atomic absorption spectrophotometry revealed that magnesium and calcium were also lost. When cells were treated with amikacin, electron microscopy of negative stains showed a substantial increase in outer membrane blebbing. Freeze fractures revealed changes in membrane fracture pattern and particle distribution, and thin sections revealed a sequential disruption of the cell envelope beginning at the outer membrane and ending at the plasma membrane. This study supports the proposal that aminoglycoside antibiotics cross the outer membrane of Pseudomonas aeruginosa by displacing metal cations necessary to stabilize the organic constituents of the membrane. Their removal results in loss of the outer membrane and the formation of transient small holes which permit the antibiotic access to the cytoplasmic membrane where it is transported into the cytoplasm.
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PMID:Amikacin disrupts the cell envelope of Pseudomonas aeruginosa ATCC 9027. 313 16

This report describes the ultrastructural features of Pseudomonas aeruginosa after freeze-etching of intact cells and enzymatically prepared spheroplasts. Freeze-etching of intact cells revealed two convex layers of the cell wall and particles within the hydrophobic interior of the cell membrane. Areas of the membrane free of particles were sometimes elevated in the form of rather large dome-shaped structures. Spheroplasts were formed from intact cells by the addition of trypsin to a reaction mixture of lysozyme and ethylenediaminetetraacetic acid. Spheroplasts contained the outer lipoid layer of the cell wall. It was possible to observe this cell wall layer in freeze-etch preparations of spheroplasts. The spheroplast membrane like that of intact cells was cleaved along a central plane to expose particles and particle-free areas.
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PMID:Surface structure of intact cells and spheroplasts of pseudomonas aeruginosa. 463 27


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