Search results for "bacteria."
showing 10 items of 4757 documents
Structural analysis of the lipid A isolated from Hafnia alvei 32 and PCM 1192 lipopolysaccharides[S]
2010
Hafnia alvei, a Gram-negative bacterium, is an opportunistic pathogen associated with mixed hospital infections, bacteremia, septicemia, and respiratory diseases. The majority of clinical symptoms of diseases caused by this bacterium have a lipopolysaccharide (LPS, endotoxin)-related origin. The lipid A structure affects the biological activity of endotoxins predominantly. Thus, the structure of H. alvei lipid A was analyzed for the first time. The major form, asymmetrically hexa-acylated lipid A built of beta-D-GlcpN4P-(1-->6)-alpha-D-GlcpN1P substituted with (R)-14:0(3-OH) at N-2 and O-3, 14:0(3-(R)-O-12:0) at N-2', and 14:0(3-(R)-O-14:0) at O-3', was identified by ESI-MS(n) and MALDI-tim…
Pyrocoll, an Antibiotic, Antiparasitic and Antitumor Compound Produced by a Novel Alkaliphilic Streptomyces Strain
2003
A new secondary metabolite was detected in the culture extract of Streptomyces sp. AK 409 by HPLC-diode-array screening. The metabolite was identified as pyrocoll, which is known to be a constituent of cigarette smoke. Pyrocoll is known as a synthetic compound, but until now had not been isolated as a natural product from a microorganism. The compound showed biological activity against various Arthrobacter strains, filamentous fungi, several pathogenic protozoa, and some human tumor cell lines.
Synthesis, characterization, and crystal structure of [Cu(cinoxacinate)2] · 2H2O complex: A square-planar CuO4 chromophore. Antibacterial studies
1995
The structural and spectroscopic properties of a new copper (II) complex of cinoxacin (HCx) have been investigated. The complex [Cu(Cx)2].2H2O crystallizes in the monoclinic system, space group P2(1)/c. The cell dimensions are: a = 7.998(2), b = 7.622(1), c = 18.955(6) A, beta = 94.38(2) degree, V = 1154.6(6) A3, Z = 2. The structure was refined to R = 0.051. The crystal is composed of [Cu(Cx)2] units and uncoordinated water molecules. The Cu(II) ion, at a center of symmetry, is coordinated to two cinoxacinate (Cx) ligands related by the inversion center. Each cinoxacinate acts as bidentate ligand bonded to the cation through its carboxylate oxygen atom and through its exocyclic carbonyl ox…
Structure and mixed spin state of the chloroiron(III) complex of 2,3,7,8,12,13,17,18-octaphenyl-5,10,15,20-tetraphenylporphyrin, Fe(dpp)Cl
2002
Abstract The chloroiron(III) complex Fe(dpp)Cl (1) of the peripherally crowded 2,3,7,8,12,13,17,18-octaphenyl-5,10,15,20-tetraphenylporphyrin or dodecaphenylporphyrin (dpp), has been synthesized and characterized by X-ray crystallography, normal-coordinate structural decomposition analysis (NSD), EPR and Mossbauer spectroscopy and magnetic susceptibility measurements. The dpp ligand present in the crystal structure of this molecule is predominantly saddle-shaped. It is also ruffled and slightly domed according to an analysis of the out-of-plane distortions performed by using NSD. This saddle deformation is significantly smaller than those observed in the chloroiron(III) complexes of the β-p…
Effect of heat activation and inactivation conditions on germination and thermal resistance parameters of Bacillus cereus spores.
2001
The effect of isothermal and non-isothermal heat activation on germination and thermoresistance of two strains of Bacillus cereus spores was studied. Results indicated that the germination after isothermal activation was lower than after non-isothermal heating. The activation rate affected the z value, which increased with faster heating rates. For each temperature and inactivation rate, the non-isothermal activation at rate of 2 degrees C/min resulted in larger D values (D90 = 4.70 min) than isothermal activation (D90 = 4.04 min). The two mathematical equations used to analyse non-isothermal data produced similar predicted D and z values, nevertheless the Hayakawa equation modified in this…
Thermal inactivation kinetics of Bacillus stearothermophilus spores using a linear temperature program.
1999
A systematic study of the inactivation kinetics of Bacillus stearothermophilus spores was carried out in nonisothermic heating conditions using a linear temperature increase program and analyzing the experimental data by means of a one-step nonlinear regression. The D and z values estimated are close to those obtained in isothermic conditions and estimated by using a two-step model, first D values are calculated, and then in the second step a z value is deduced (D(121 degrees C) = 3.08 and 4.38 min, respectively, and z = 7 and 7.9 degrees C, respectively). No convergence problems were observed when using the one-step nonlinear regression proposed. The results indicated that the methodology …
High gas pressure: An innovative method for the inactivation of dried bacterial spores
2012
In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pres…
Pathogenicity of intrathoracically administrated Bacillus thuringiensis spores in Blatta orientalis.
2006
Abstract The ability of Bacillus thuringiensis to produce septicaemia in Periplaneta americana and Blatta orientalis has been investigated. Spores and crystals from several wild-type strains as well as spores of a B. thuringiensis crystal-deficient mutant, were first orally administrated at high doses, and no significant mortality was recorded. Intrathoracic injection of spore suspensions in P. americana revealed that this species is not very susceptible to B. thuringiensis spores. B. orientalis , by contrast, was found to be very susceptible to B. thuringiensis , with a LD 50 of about 35,000 spores, that is similar to that reported on Lepidoptera challenged with parenterally injected B. th…
Abundance of cellular material and proteins in the atmosphere.
2005
Suspended atmospheric particles play a crucial role in any global climate scenario: They can both enforce and suppress radiative forcing. In developing climate modeling further, a deeper understanding of atmospheric aerosol is needed. Because of extreme local and temporal variations, proper incorporation of aerosols into models requires modeling of the aerosol itself. It turns out that cellular material and proteins compose up to 25% of the atmospheric aerosol. Consequently, the source strength of the biogenic aerosol in general must be corrected and should be estimated on the order of other major aerosol sources.
Bacterial growth and biological properties of Cymbopogon schoenanthus and Ziziphus lotus are modulated by extraction conditions
2020
Abstract The present study aims to evaluate the antibacterial activity and biological properties of two traditional Saharian plants (Cymbopogon schoenanthus and Ziziphus lotus). The plant extracts were obtained by using a different combination of extraction methods (conventional vs. ultrasound-assisted) and solvents (water vs. ethanol:water (50:50, v/v)). The antioxidant profile, anti-inflammatory activity and impact on bacterial growth (foodborne and probiotic bacteria) of the obtained extracts were assessed. The plant species showed the hierarchically more important role in determining the biological properties of the extracts, followed by extraction solvent and extraction conditions. Con…