Bactericidal effect of lactoferrin on Legionella pneumophila: effect of the physiological state of the organism

1989 ◽  
Vol 35 (11) ◽  
pp. 1048-1051 ◽  
Author(s):  
Carol A. Bortner ◽  
Roland R. Arnold ◽  
Richard D. Miller
Keyword(s):  
Legionella Pneumophila ◽  
Immunofluorescence Microscopy ◽  
Physiological State ◽  
Bactericidal Effect ◽  
Growth Conditions ◽  
Temperature Dependent ◽  
Killing Activity ◽  
Ph Dependent

Lactoferrin has been previously shown to be bactericidal for Legionella pneumophila. The current study showed that CaCl2, Mg(NO3)2, and MgCl2, but not NaCl, blocked killing. Activity was pH dependent with the greatest activity at 5.0. Sensitivity of the organism was dramatically affected by the growth conditions. Log phase 12 h, broth-grown cells were most sensitive, with older cultures becoming more resistant. Plate-grown cells were completely resistant. Lactoferrin binding, as detected by immunofluorescence microscopy, was temperature dependent (no binding at 4 °C), but was independent of killing.Key words: Legionella pneumophila, lactoferrin, mucosal proteins.

Temperature Dependent Quasi-Periodic Facetting of AlAs Grown by MBE on (100) GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
Richard Mirin ◽  
Mohan Krishnamurthy ◽  
James Ibbetson ◽  
Arthur Gossard ◽  
John English ◽  
...  
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
High Energy Electron ◽  
Temperature Dependent ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Facet Formation

AbstractHigh temperature (≥ 650°C) MBE growth of AlAs and AlAs/GaAs superlattices on (100) GaAs is shown to lead to quasi-periodic facetting. We demonstrate that the facetting is only due to the AlAs layers, and growth of GaAs on top of the facets replanarizes the surface. We show that the roughness between the AlAs and GaAs layers increases with increasing number of periods in the superlattice. The roughness increases to form distinct facets, which rapidly grow at the expense of the (100) surface. Within a few periods of the initial facet formation, the (100) surface has disappeared and only the facet planes are visible in cross-sectional transmission electron micrographs. At this point, the reflection high-energy electron diffraction pattern is spotty, and the specular spot is a distinct chevron. We also show that the facetting becomes more pronounced as the substrate temperature is increased from 620°C to 710°C. Atomic force micrographs show that the valleys enclosed by the facets can be several microns long, but they may also be only several nanometers long, depending on the growth conditions.

Antimicrobial Effects of d-3-Phenyllactic Acid on Listeria monocytogenes in TSB-YE Medium, Milk, and Cheese

1998 ◽  
Vol 61 (10) ◽  
pp. 1281-1285 ◽  
Author(s):  
VIRGINIE DIEULEVEUX ◽  
MICHELINE GUÉGUEN
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Phase ◽  
Physiological State ◽  
Geotrichum Candidum ◽  
Bactericidal Effect ◽  
Exponential Growth Phase ◽  
Bacteriostatic Effect ◽  
Experimental Conditions ◽  
Phenyllactic Acid ◽  
Whole Milk

d-3-Phenyllactic acid is a compound with anti-Listeria activity which is produced and secreted by the yeastlike fungus, Geotrichum candidum. This compound has a bactericidal effect independent of the physiological State of Listeria monocytogenes when added at a concentration of 7 mg/ml to tryptic soy broth supplemented with yeast extract (TSB-YE). An initial L. monocytogenes population of 105 CFU/ml was reduced 100-fold (2 log) after 4 days of culture at 25 °C in TSB-YE containing d-3-phenyllactic acid. The Listeria population was reduced 1,000-fold (3 log) when the compound was added during the exponential growth phase, and was reduced to less than 10 CFU/ml when it was added during the stationary phase. d-3-Phenyllactic acid had a bacteriostatic effect in UHT whole milk, reducing the population by 4.5 log, to give fewer cells than in the control after 5 days of culture. The results obtained with L. monocytogenes at concentrations of 105 and 103 CFU/ml in cheese curds were less conclusive. d-3-Phenyllactic acid was 10 times less active than nisin in our experimental conditions (TSB-YE at 25°C).

Evaluation of bacteriophages during the treatment of sludge

2002 ◽  
Vol 46 (10) ◽  
pp. 189-194 ◽  
Author(s):  
B. Mignotte-Cadiergues ◽  
C. Gantzer ◽  
L. Schwartzbrod
Keyword(s):  
Bacteroides Fragilis ◽  
Temperature Dependent ◽  
Treatment Methods ◽  
Somatic Coliphages ◽  
Viral Contamination ◽  
Log Reduction ◽  
Ph Dependent ◽  
Somatic Coliphage ◽  
Phage Inactivation

The aim of this work was to determine the effect of liming and composting on the fate of three bacteriophages (somatic coliphages, F-RNA phages, Bacteroides fragilis phages) considered as potential indicators of viral contamination. It was shown that the three bacteriophages studied exhibited variable densities in sludge. Somatic coliphages were most abundant (104 to 105 .10 g−1 DM) then F-RNA bacteriophages (102 to 104.10 g−1 DM) and Bacteroides fragilis phages (101 to 102.10 g−1 DM). The efficacy of liming was found to be pH dependent but also sludge dependent. The pH allowing 99% elimination of somatic coliphage is close to 9 for solid sludges and close to 13.5 for liquid sludges. For composting, our findings clearly demonstrated that phage inactivation is very clearly temperature-dependent. For temperatures reaching 70°, there is a 5 log reduction in somatic coliphages while for temperature in the 50-55°C range, the drop off is only 2 log. Considering the efficacy of the treatment methods, it is clear that the well-established industrial procedures that reach temperatures in the 60-70°C range totally inactivate all 3 phages tested and present in sludge before composting.

scholarly journals A model for variable phytoplankton stoichiometry based on cell protein regulation

2013 ◽  
Vol 10 (2) ◽  
pp. 3241-3279
Author(s):  
J. A. Bonachela ◽  
S. D. Allison ◽  
A. C. Martiny ◽  
S. A. Levin
Keyword(s):  
Physiological State ◽  
Single Point ◽  
Nutrient Content ◽  
Growth Conditions ◽  
Marine Phytoplankton ◽  
Cell Protein ◽  
Nitrogen And Phosphorus ◽  
Elemental Ratios ◽  
Regulatory Processes ◽  
Complex Interactions

Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. The existence of a wide co-limitation zone affects the standard picture for species competing for nitrogen and phosphorus, which shows here a much richer pattern. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.

scholarly journals Bactericidal Effect of Disinfectants Against Legionella pneumophila and Legionella bozemanii

1984 ◽  
Vol 58 (2) ◽  
pp. 130-136
Author(s):  
Katsuhiko SAWATARI ◽  
Koichi WATANABE ◽  
Hiroko NAKASATO ◽  
Hironobu KOGA ◽  
Naomi ITO ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Bactericidal Effect

Adsorption, desorption, and activity of glucose oxidase on selected clay species

1976 ◽  
Vol 22 (5) ◽  
pp. 684-693 ◽  
Author(s):  
H. W. Morgan ◽  
C. T. Corke
Keyword(s):  
Hydrogen Bonding ◽  
Protein Structure ◽  
Cation Exchange ◽  
Glucose Oxidase ◽  
Isoelectric Point ◽  
Active Form ◽  
Temperature Dependent ◽  
Specific Activities ◽  
Ph Dependent ◽  
Adsorption Desorption

The adsorption of the enzyme glucose oxidase (EC 1.1.3.4) to clays followed the pattern described for other proteins as being pH dependent. Maximum adsorption occurred at or below the isoelectric point of the enzyme. The amount of enzyme adsorbed to clay was influenced by the type of clay used, and also the saturating cations. Initially adsorbed enzyme showed low specific activities, and as amounts of enzyme adsorbed approached maximum saturation of clay, specific activities increased approaching that determined for free enzyme.The adsorption of glucose oxidase involved a temperature-independent cation-exchange mechanism, and enzyme adsorbed to surfaces of clay could be desorbed in active form by elevation of pH of suspending solution. This was followed by a slower temperature-dependent fixation, probably by hydrogen bonding, which resulted in protein being irreversibly adsorbed to clay surfaces.It is proposed that on adsorption of glucose oxidase to clay surfaces unravelling of the protein structure occurred, which allowed penetration of protein into the interlamellar spaces of montmorillonite. This proposal was based on the observed expansion of montmorillonite to 23 Å, and the decreases in amount of a second-protein lysozyme adsorbed with extended incubation times of glucose oxidase – clay complexes at pH 4.5.

scholarly journals Effect of polyamines on the stability of brain-cortex ribosomes

1969 ◽  
Vol 114 (4) ◽  
pp. 847-854 ◽  
Author(s):  
R. K. Datta ◽  
Suchandra Sen ◽  
J. J. Ghosh
Keyword(s):  
Melting Temperature ◽  
Brain Cortex ◽  
Temperature Dependent ◽  
Enzymic Digestion ◽  
Ph Dependent ◽  
High Concentrations ◽  
The Stability ◽  
Goat Brain

1. Ribosomes isolated from the cortex tissue of goat brain contain very small amounts of spermidine and spermine. Ribosomes isolated from spermidine-treated slices have a higher spermidine content. 2. The polyamines partially prevent the temperature-dependent breakdown of ribosomes into acid-soluble nucleotides. 3. The ‘melting’ temperature of ribosomes rises slightly when the ribosomes are heated slowly in the presence of polyamines. 4. The pH-dependent breakdown of ribosomes into protein, RNA and acid-soluble nucleotide is markedly decreased by polyamines present in media in which ribosomes are suspended. 5. The breakdown of ribosomes in the presence of high concentrations of salts and EDTA is partially checked by the concurrent presence of polyamines. 6. Spermidine and spermine make ribosomes less susceptible to enzymic digestion by crystalline trypsin and ribonuclease.

scholarly journals TheBeauveria bassianaGas3 β-Glucanosyltransferase Contributes to Fungal Adaptation to Extreme Alkaline Conditions

2018 ◽  
Vol 84 (15) ◽  
Author(s):  
Zhibing Luo ◽  
Tongbing Zhang ◽  
Pengfei Liu ◽  
Yuting Bai ◽  
Qiyan Chen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Pathogenic Fungus ◽  
Growth Conditions ◽  
Alkaline Ph ◽  
Ph Responsive ◽  
Content Type ◽  
Cell Wall Remodeling ◽  
Alkaline Conditions ◽  
Increased Sensitivity ◽  
Ph Dependent

ABSTRACTFungal β-1,3-glucanosyltransferases are cell wall-remodeling enzymes implicated in stress response, cell wall integrity, and virulence, with most fungal genomes containing multiple members. The insect-pathogenic fungusBeauveria bassianadisplays robust growth over a wide pH range (pH 4 to 10). A random insertion mutant library screening for increased sensitivity to alkaline (pH 10) growth conditions resulted in the identification and mapping of a mutant to a β-1,3-glucanosyltransferase gene (Bbgas3).Bbgas3expression was pH dependent and regulated by the PacC transcription factor, which activates genes in response to neutral/alkaline growth conditions. Targeted gene knockout ofBbgas3resulted in reduced growth under alkaline conditions, with only minor effects of increased sensitivity to cell wall stress (Congo red and calcofluor white) and no significant effects on fungal sensitivity to oxidative or osmotic stress. The cell walls of ΔBbgas3aerial conidia were thinner than those of the wild-type and complemented strains in response to alkaline conditions, and β-1,3-glucan antibody and lectin staining revealed alterations in cell surface carbohydrate epitopes. The ΔBbgas3mutant displayed alterations in cell wall chitin and carbohydrate content in response to alkaline pH. Insect bioassays revealed impaired virulence for the ΔBbgas3mutant depending upon the pH of the media on which the conidia were grown and harvested. Unexpectedly, a decreased median lethal time to kill (LT50, i.e., increased virulence) was seen for the mutant using intrahemocoel injection assays using conidia grown at acidic pH (5.6). These data show that BbGas3 acts as a pH-responsive cell wall-remodeling enzyme involved in resistance to extreme pH (>9).IMPORTANCELittle is known about adaptations required for growth at high (>9) pH. Here, we show that a specific fungal membrane-remodeling β-1,3-glucanosyltransferase gene (Bbgas3) regulated by the pH-responsive PacC transcription factor forms a critical aspect of the ability of the insect-pathogenic fungusBeauveria bassianato grow at extreme pH. The loss ofBbgas3resulted in a unique decreased ability to grow at high pH, with little to no effects seen with respect to other stress conditions, i.e., cell wall integrity and osmotic and oxidative stress. However, pH-dependent alternations in cell wall properties and virulence were noted for the ΔBbgas3 mutant. These data provide a mechanistic insight into the importance of the specific cell wall structure required to stabilize the cell at high pH and link it to the PacC/Pal/Rim pH-sensing and regulatory system.

The Effect of Initial Growth Conditions on the Tilting of Lattice Planes in InP-ON-GaAs Heterostructures

1991 ◽  
Vol 238 ◽  
Author(s):  
Ferenc Riesz ◽  
K. Lischka ◽  
K. Rakennus ◽  
T. Hakkarainen ◽  
A. Pesek ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Initial Growth ◽  
Lattice Plane ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Gas Source ◽  
Gaas Substrates ◽  
Nucleation Model ◽  
Lattice Planes ◽  
Lower Temperature

ABSTRACTThe relative misorientation (tilt) between the epilayer and substrate (400) lattice planes of InP epilayers grown by gas-source molecular beam epitaxy on (100) GaAs substrates misoriented towards the (110) plane was studied by high resolution x-ray diffraction. For the growth temperature of 490–500°C, the direction of the relative tilt was nearly coincident with the direction of the substrate lattice plane tilting. In contrary, when a buffer layer was deposited at a lower temperature of 400–450°C prior to growth, an azimuthal rotation of about 45° was found between the directions of the relative tilt and the substrate lattice plane tilting. In order to explain the results, a temperature-dependent anisotropic nucleation model is proposed.

scholarly journals Silencing of natural transformation by an RNA chaperone and a multitarget small RNA

2016 ◽  
Vol 113 (31) ◽  
pp. 8813-8818 ◽  
Author(s):  
Laetitia Attaiech ◽  
Aïda Boughammoura ◽  
Céline Brochier-Armanet ◽  
Omran Allatif ◽  
Flora Peillard-Fiorente ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Natural Transformation ◽  
Bacterial Species ◽  
Physiological State ◽  
Uptake System ◽  
Dna Uptake ◽  
Exogenous Dna ◽  
Major Mechanism ◽  
Transcriptional Gene Regulation ◽  
High Level

A highly conserved DNA uptake system allows many bacteria to actively import and integrate exogenous DNA. This process, called natural transformation, represents a major mechanism of horizontal gene transfer (HGT) involved in the acquisition of virulence and antibiotic resistance determinants. Despite evidence of HGT and the high level of conservation of the genes coding the DNA uptake system, most bacterial species appear non-transformable under laboratory conditions. In naturally transformable species, the DNA uptake system is only expressed when bacteria enter a physiological state called competence, which develops under specific conditions. Here, we investigated the mechanism that controls expression of the DNA uptake system in the human pathogenLegionella pneumophila. We found that a repressor of this system displays a conserved ProQ/FinO domain and interacts with a newly characterizedtrans-acting sRNA, RocR. Together, they target mRNAs of the genes coding the DNA uptake system to control natural transformation. This RNA-based silencing represents a previously unknown regulatory means to control this major mechanism of HGT. Importantly, these findings also show that chromosome-encoded ProQ/FinO domain-containing proteins can assisttrans-acting sRNAs and that this class of RNA chaperones could play key roles in post-transcriptional gene regulation throughout bacterial species.

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