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1.
Nutr Metab Cardiovasc Dis ; 31(8): 2458-2470, 2021 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-34090773

RESUMO

BACKGROUND AND AIMS: Insufficient dietary fiber (DF) intake is associated with increased blood pressure (BP) and the mode of action is unclear. The intake of DF supplements by participants in previous interventional studies was still far below the amount recommended by the World Health Organization. Therefore, this study aims to explore the effect of supplementing relatively sufficient DF on BP and gut microbiota in patients with essential hypertension (HTN). METHODS AND RESULTS: Fifty participants who met the inclusion criteria were randomly divided into the DF group (n = 25) and control group (n = 25). All the participants received education on regular dietary guidance for HTN. In addition to dietary guidance, one bag of oat bran (30 g/d) supplement (containing DF 8.9 g) was delivered to the DF group. The office BP (oBP), 24 h ambulatory blood pressure, and gut microbiota were measured at baseline and third month. After intervention, the office systolic blood pressure (oSBP; P < 0.001) and office diastolic blood pressure (oDBP; P < 0.028) in the DF group were lower than those in the control group. Similarly, the changes in 24hmaxSBP (P = 0.002), 24hmaxDBP (P = 0.001), 24haveSBP (P < 0.007), and 24haveDBP (P = 0.008) were greater in the DF group than in the control group. The use of antihypertensive drugs in the DF group was significantly reduced (P = 0.021). The ß diversity, including Jaccard (P = 0.008) and Bray-Curtis distance (P = 0.004), showed significant differences (P < 0.05) between two groups by the third month. The changes of Bifidobacterium (P = 0.019) and Spirillum (P = 0.006) in the DF group were significant. CONCLUSIONS: Increased DF (oat bran) supplement improved BP, reduced the amount of antihypertensive drugs, and modulated the gut microbiota. TRIAL REGISTRATION NUMBER: ChiCTR1900024055.


Assuntos
Avena , Bifidobacterium/crescimento & desenvolvimento , Pressão Sanguínea , Fibras na Dieta/administração & dosagem , Grão Comestível , Hipertensão Essencial/dietoterapia , Microbioma Gastrointestinal , Spirillum/crescimento & desenvolvimento , Adulto , Monitorização Ambulatorial da Pressão Arterial , China , Disbiose , Hipertensão Essencial/diagnóstico , Hipertensão Essencial/microbiologia , Hipertensão Essencial/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Nutritivo , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento
2.
PLoS One ; 14(12): e0225477, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31809502

RESUMO

Assimilable organic carbon (AOC) is known to correlate with microbial growth, which can consequently degrade drinking water quality. Despite this, there is no standardised AOC test that can be applied to drinking water distribution systems (DWDS). Herein we report the development of a quick, robust AOC that incorporates known strains Pseudomonas fluorescens strain P-17 and Spirillum strain NOX, a higher inoculum volume and enumeration using flow cytometry to generate a quicker (total test time reduced from 14 to 8 days), robust method. We apply the developed AOC test to twenty drinking water treatment works (WTW) to validate the method reproducibility and resolution across a wide range of AOC concentrations. Subsequently, AOC was quantified at 32 sample points, over four DWDS, for a year in order to identify sinks and sources of AOC in operative networks. Application of the developed AOC protocol provided a previously unavailable insight and novel evidence of pipes and service reservoirs exhibiting different AOC and regrowth behaviour. Observed correlations between AOC and microbial growth highlight the importance of monitoring AOC as an integral part of managing drinking water quality at the consumers tap.


Assuntos
Carbono/análise , Água Potável/normas , Compostos Orgânicos/análise , Microbiologia da Água/normas , Qualidade da Água/normas , Carbono/metabolismo , Água Potável/química , Água Potável/microbiologia , Citometria de Fluxo/métodos , Compostos Orgânicos/metabolismo , Pseudomonas fluorescens/metabolismo , Reprodutibilidade dos Testes , Spirillum/metabolismo , Purificação da Água
3.
Chemosphere ; 222: 205-213, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30708154

RESUMO

Assimilable organic carbon (AOC) serves as an indicator of the biostability of drinking water distribution systems; however, the properties of the released organic metabolites by Pseudomonas fluorescens (P17) and Spirillum (NOX) used in AOC bioassays are seldom discussed. In this study, fluorescence excitation emission matrix (FEEM) was selected to characterize organic metabolites after substrate biotransformation and their divergences at different growth stages of both strains in AOC bioassay. Excellent correlation between ATP and colony-forming units (CFUs) was observed for both strains. The concentration of ATP per colony was six times higher in the P17 strain than in the NOX strain. A retarding phenomenon was observed for the NOX strain in the presence of high acetate-C content (100-150 µg acetate-C/L). The fluorescence wavelength peaks were wider for the protein-like substance released by the P17 strain than for those released by the NOX strain. However, fluorescent fulvic-like substances only existed in the NOX strain. Relative humus accumulation (RHA), the ratio of protein-like fluorescence intensity to humus-like fluorescence intensity, decreased in the P17 strain but substantially increased in the NOX strain in the logarithmic growth phase. RHA showed a descending trend for the P17 strain as compared to that of the NOX strain during the progress from logarithmic to stationary growth phase at three different acetate-C concentrations; however, the opposite was observed at 100 µg acetate-C/L, indicating that high acetate-C content may affect the properties of released organic matter from both strains.


Assuntos
Carbono/análise , Água Potável/normas , Pseudomonas fluorescens/metabolismo , Spirillum/metabolismo , Acetatos/farmacologia , Corantes , Compostos Orgânicos/análise , Compostos Orgânicos/metabolismo , Purificação da Água
4.
Nanoscale ; 8(2): 1100-7, 2016 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-26666198

RESUMO

This report shows that immunomagnetic beads (IMBs) can act as the optical readout for assays, in addition to serving as the carrier for purification/separation. Under the influence of an external magnet, IMBs are attracted to coat one side of a test tube. IMBs specifically bound to targets can form a narrow brown stripe, whereas free IMBs will form a diffuse, yellow coating on the side of the test tube. Target analytes can aggregate initially dispersed IMBs in a sample concentration-dependent manner, yielding a color change from yellow to brown that can be seen with the naked eye. This assay combines the convenience of a lateral flow assay, allowing a one-step assay to finish within 15 min, with the sensitivity of an enzyme-linked immonosorbent assay.


Assuntos
Biomarcadores Tumorais/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Separação Imunomagnética/métodos , Neoplasias/diagnóstico , Escherichia coli/isolamento & purificação , Humanos , Magnetismo , Nanotecnologia/métodos , Neoplasias/genética , Óptica e Fotônica , Sistemas Automatizados de Assistência Junto ao Leito , Salmonella/isolamento & purificação , Shigella/isolamento & purificação , Spirillum/isolamento & purificação , Staphylococcus aureus/isolamento & purificação , Estresse Mecânico
6.
Res Microbiol ; 161(4): 276-83, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20178843

RESUMO

Magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats. Because of their fastidious requirements for growth conditions, only very few axenic MTB cultures have been obtained worldwide. In this study, we report a novel marine magnetotactic spirillum axenic culture, designated as QH-2, isolated from the China Sea. It was able to grow in semi-solid or liquid chemically defined medium. The cells were amphitrichously flagellated and contained one single magnetosome chain with an average number of 16 magnetosomes per cell. Phosphate and lipid granules were also observed in the cells. Both rock magnetism and energy-dispersive X-ray spectroscopy characterizations indicated that the magnetosomes in QH-2 were single-domain magnetites (Fe(3)O(4)). QH-2 cells swam mostly in a straight line at a velocity of 20-50 microm/s and occasionally changed to a helical motion. Unlike other magnetotactic spirilla, QH-2 cells responded to light illumination. As a consequence of illumination, the cells changed the direction in which they swam from parallel to the magnetic field to antiparallel. This response appears to be similar to the effect of an increase in [O(2)]. Analysis of the QH-2 16S rRNA sequence showed that it had greater than 11% sequence divergence from freshwater magnetotactic spirilla. Thus, the marine QH-2 strain seems to be both phylogenetically and magnetotactically distinct from the freshwater Magnetospirillum spp. studied previously.


Assuntos
Magnetismo , Água do Mar/microbiologia , Spirillum/classificação , Spirillum/isolamento & purificação , China , Magnetossomos/química , Magnetossomos/genética , Magnetossomos/metabolismo , Dados de Sequência Molecular , Filogenia , Spirillum/química , Spirillum/genética
7.
Appl Environ Microbiol ; 75(23): 7385-90, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19820156

RESUMO

Assimilable organic carbon (AOC) is an important parameter governing the growth of heterotrophic bacteria in drinking water. Despite the recognition that variations in treatment practices (e.g., disinfection, coagulation, selection of filter media, and watershed protection) can have dramatic impacts on AOC levels in drinking water, few water utilities routinely measure AOC levels because of the difficulty of the method. To simplify the method, the Pseudomonas fluorescens P-17 and Spirillum sp. strain NOX test bacteria were mutagenized by using luxCDABE operon fusion and inducible transposons to produce bioluminescent strains. The growth of these strains can easily be monitored with a programmable luminometer to determine the maximum cell yield via luminescence readings, and these values can be fitted to the classical Monod growth curve to determine bacterial growth kinetics and the maximum growth rate. Standard curves using acetate carbon (at concentrations ranging from 0 to 1,000 microg/liter) resulted in coefficients of determination (r(2)) between luminescence units and acetate carbon levels of 0.95 for P-17 and 0.89 for NOX. The bioluminescence test was used to monitor reclaimed water, in which average AOC levels range between 150 and 1,400 microg/liter acetate carbon equivalents. Comparison of the conventional AOC assay and the bioluminescent assay produced an r(2) of 0.92.


Assuntos
Carbono/metabolismo , Compostos Orgânicos/análise , Pseudomonas fluorescens/metabolismo , Spirillum/metabolismo , Purificação da Água/métodos , Água/química , Genes Reporter , Luciferases/genética , Luciferases/metabolismo , Luminescência , Pseudomonas fluorescens/genética , Spirillum/genética
8.
Int J Syst Evol Microbiol ; 59(Pt 11): 2916-20, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19625415

RESUMO

A novel obligately organotrophic, facultatively microaerophilic spirillum, designated strain D-427(T), was isolated from sulfidic sludge of a municipal wastewater-treatment plant. Cells were Gram-negative, large and highly motile due to bipolar tufts of flagella covered with mucous sheaths. Coccoid cells were sometimes formed. Strain D-427(T) grew optimally at pH 7.5-7.8 and 28 degrees C in the presence of 2 % O(2) in the gas phase. The organism showed oxidase and very low catalase activity. The isolate grew chemo-organotrophically with a limited number of organic acids as substrates. The DNA G+C content was 38.0 mol% (T(m)). Phylogenetic analysis of the 16S rRNA gene sequence placed strain D-427(T) in the genus Spirillum within the class Betaproteobacteria. The 16S rRNA gene sequence similarity between strain D-427(T) and Spirillum volutans ATCC 19554(T), the type strain of the single species of the genus, was 98.6 %. The low level of DNA-DNA hybridization and different phenotypic properties indicate that strain D-427(T) is clearly distinguishable from Spirillum volutans. No strain of S. volutans is available from any established culture collection or from the authors who described this species. Therefore, on the basis of phenotypic and genotypic data and the fact that the type and single species of the genus Spirillum cannot be included in any scientific study, since the type strain has been lost, we propose to assign strain D-427(T) as a novel species of the genus Spirillum, Spirillum winogradskyi sp. nov. (type strain D-427(T) =DSM 12756(T) =VKM B-2518(T)), and we request that the Judicial Commission place the name Spirillum volutans on the list of rejected names if a suitable type strain is not found or a neotype is not proposed within 2 years following the publication of this paper. An emended description of the genus Spirillum is also provided.


Assuntos
Esgotos/microbiologia , Spirillum/classificação , Spirillum/isolamento & purificação , DNA Bacteriano/genética , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Spirillum/genética
9.
Vet Microbiol ; 133(3): 211-28, 2009 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-19008054

RESUMO

Rat bite fever (RBF) is a bacterial zoonosis for which two causal bacterial species have been identified: Streptobacillis moniliformis and Spirillum minus. Haverhill fever (HF) is a form of S. moniliformis infection believed to develop after ingestion of contaminated food or water. Here the infectious agents, their host species, pathogenicity (virulence factors and host susceptibility), diagnostic methods, therapy, epidemiology, transmission and prevention are described. Special emphasis is given on information from the field of laboratory animal microbiology and suggestions for future research.


Assuntos
Febre por Mordedura de Rato/microbiologia , Spirillum , Streptobacillus , Animais , Humanos , Ratos
11.
Mikrobiologiia ; 75(2): 212-20, 2006.
Artigo em Russo | MEDLINE | ID: mdl-16758869

RESUMO

New microaerophilic sulfur-oxidizing spirilla were isolated from hydrogen sulfide sludge of wastewater treatment plants. Strains D-427 and D-430 have spiral cells that are highly motile due to bipolar flagellum bundles covered with mucous sheaths. Under a phase-contrast microscope, these bundles are visible as single polar flagella. Spheroplasts are formed in the stationary growth phase. Both strains are obligate organotrophs able to oxidize a number of reduced sulfur compounds. The oxidation of sulfide and polysulfide leads to the formation of intracellular globules of elemental sulfur; thiosulfate oxidation results in tetrathionate accumulation in the medium. The cells are unable to utilize reduced sulfur compounds in the energy metabolism; their oxidation is caused by a chemical interaction with H2O2 and O2, synthesized in the electron transport chain. Both strains are obligate microaerophiles with an optimal oxygen concentration in the gas phase of 2 and 0.8% for strains D-427 and D-430, respectively. The strains utilize a limited number of organic acids as growth substrates, mainly tricarboxylic-acid-cycle intermediates. The DNA G+C content is 38.0 mol % (T(m)) for strain D-427 and 38.9 mol % for strain D-430. Phylogenetic analysis, based on the comparison of 16S rRNA gene sequences, revealed that the new isolates of sulfur spirilla are the most closely related to Spirillum volutans, the type species of the genus (97.4% similarity). They were assigned to the genus Spirillum within the class Beta-proteobacteria as two new species, S. winogradskii sp. nov. (D-427T = DSM 12756T) and S. kriegii sp. nov. (B-430T = BKM B-2372T). The emended description of the genus Spirillum is provided.


Assuntos
Esgotos/microbiologia , Spirillum/metabolismo , Spirillum/ultraestrutura , Enxofre/metabolismo , Microbiologia da Água , Genótipo , Oxigênio/farmacologia , Filogenia , Spirillum/isolamento & purificação , Sulfetos/metabolismo
12.
Environ Technol ; 27(4): 377-86, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16583822

RESUMO

The aim of this study was to characterize the influence of free chlorine residual on biofilm formation in a chlorinated system in which the biodegradable organic matter (BOM) was limited. The biofilm community was characterized through a community-level physiological profile (CLPP) that was generated using the Biolog GN microplate-based community-level assay. The chlorinated system was run at chlorine residual concentrations of 0.3, 0.5, and 1.0 mg l(-1) with the provision of BOM-limited tap water (0.01 mg l(-1) as assimilable organic carbon and 0.06 mg l(-1) as biodegradable dissolved organic carbon). For comparison, an unchlorinated system was operated in parallel under the same condition. The number of viable heterotrophic bacteria in the biofilm that formed in the chlorinated system over the 3 months of operation averaged 7.2 x 10(3), 4.8 x 10, and 1.6 x 10 CFU cm(-2) for the chlorine residual concentrations of 0.3, 0.5, and 1.0 mg l(-1), respectively. In the unchlorinated system, the average bacterial content was 1.1 x 10(6) CFU cm(-2). Using measures of substrate utilization rate, substrate utilization diversity, and metabolic potential index (MPI), the CLPP patterns demonstrated that the metabolic potentials of the biofilm communities decreased markedly as the chlorine residual levels increased. In particular, the community level of the biofilm that formed in the system with chlorine residual concentration of 1.0 mg l(-1) was the lowest of any biofilm under the tested conditions. The results implied that chlorine residual had a positive biocidal effect on the metabolic potential and/or functional potential of the biofilm community, especially when the BOM level was low. In addition, BOM limitation by itself was not sufficient to control biofilm formation.


Assuntos
Biofilmes/crescimento & desenvolvimento , Cloro/metabolismo , Compostos Orgânicos/metabolismo , Purificação da Água/métodos , Abastecimento de Água , Biodegradação Ambiental , Contagem de Colônia Microbiana , Monitoramento Ambiental , Pseudomonas fluorescens , Spirillum , Temperatura , Microbiologia da Água
13.
Mikrobiologiia ; 74(1): 17-25, 2005.
Artigo em Russo | MEDLINE | ID: mdl-15835774

RESUMO

Oxidation of reduced sulfur compounds by microaerophilic sulfur bacterium Spirillum winogradskii was found to occur only concomitantly with consumption of an organic substrate and was not linked to their utilization as electron donors in energy metabolism. No enzymes of dissimilatory sulfur metabolism were found in the cells of the sulfur bacterium oxidizing thiosulfate to tetrathionate; oxidation of thiosulfate and sulfide was caused by their reaction with reactive oxygen species (ROS), mostly H2O2 produced in the course of aerobic growth. Decreased lytic effect of ROS in the presence of thiosulfate resulted in a twofold increase in the cell yield under aerobic conditions and more efficient substrate utilization. The latter effect was caused by decreased expense of energy for the biosynthesis of oxygen-protecting polysaccharides. The stimulatory effect of thiosulfate on the growth processes was due to the activation of a number of TCA cycle enzymes producing the intermediates for constructive metabolism, especially of the NADP-dependent malic enzyme. As a result of thiosulfate-induced synthesis of SH-containing cell components, the integral antioxidative activity increased 1.5-fold.


Assuntos
Oxigênio/metabolismo , Spirillum/metabolismo , Compostos de Enxofre/metabolismo , Trifosfato de Adenosina/biossíntese , Peróxido de Hidrogênio/metabolismo , Malato Desidrogenase/metabolismo , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Spirillum/crescimento & desenvolvimento , Tiossulfatos/metabolismo
14.
Environ Microbiol ; 7(5): 723-36, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15819854

RESUMO

The bacterioneuston is defined as the community of bacteria present within the neuston or sea surface microlayer. Bacteria within this layer were sampled using a membrane filter technique and bacterial diversity was compared with that in the underlying pelagic coastal seawater using molecular ecological techniques. 16S rRNA gene libraries of approximately 500 clones were constructed from both bacterioneuston and the pelagic water samples and representative clones from each library were sequenced for comparison of bacterial diversity. The bacterioneuston was found to have a significantly lower bacterial diversity than the pelagic seawater, with only nine clone types (ecotaxa) as opposed to 46 ecotaxa in the pelagic seawater library. Surprisingly, the bacterioneuston clone library was dominated by 16S rRNA gene sequences affiliated to two groups of organisms, Vibrio spp. which accounted for over 68% of clones and Pseudoalteromonas spp. accounting for 21% of the library. The dominance of these two 16S rRNA gene sequence types within the bacterioneuston clone library was confirmed in a subsequent gene probing experiment. 16S rRNA gene probes specific for these groups of bacteria were designed and used to probe new libraries of 1000 clones from both the bacterioneuston and pelagic seawater DNA samples. This revealed that 57% of clones from the bacterioneuston library hybridized to a Vibrio sp.-specific 16S rRNA gene probe and 32% hybridized to a Pseudoalteromonas sp.-specific 16S rRNA gene probe. In contrast, the pelagic seawater library resulted in only 13% and 8% of 16S rRNA gene clones hybridizing to the Vibrio sp. and Pseudoalteromonas sp. probes respectively. Results from this study suggest that the bacterioneuston contains a distinct population of bacteria and warrants further detailed study at the molecular level.


Assuntos
Bactérias Gram-Negativas/isolamento & purificação , Água do Mar/microbiologia , Microbiologia da Água , Aeromonas/genética , Aeromonas/isolamento & purificação , Sequência de Bases , DNA Bacteriano/química , DNA Bacteriano/genética , Biblioteca Gênica , Variação Genética , Bactérias Gram-Negativas/genética , Dados de Sequência Molecular , Mar do Norte , Filogenia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Pseudoalteromonas/genética , Pseudoalteromonas/isolamento & purificação , Pseudomonas/genética , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética , Alinhamento de Sequência , Spirillum/genética , Spirillum/isolamento & purificação , Vibrio/genética , Vibrio/isolamento & purificação
15.
Appl Environ Microbiol ; 70(2): 850-4, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14766564

RESUMO

The assimilable organic carbon (AOC) test is a standardized measure of the bacterial growth potential of treated water. We describe the design and initial development of an AOC assay that uses bioluminescent derivatives of AOC test bacteria. Our assay is based on the observation that bioluminescence peaks at full cell yield just prior to the onset of the stationary phase during growth in a water sample. Pseudomonas fluorescens P-17 and Spirillum sp. strain NOX bacteria were mutagenized with luxCDABE operon fusion and inducible transposons and were selected on minimal medium. Independent mutants were screened for high luminescence activity and predicted AOC assay sensitivity. All mutants tested were able to grow in tap water under AOC assay conditions. Strains P-17 I5 (with p-aminosalicylate inducer) and NOX I3 were chosen for use in the bioluminescence AOC test. Peak bioluminescence and plate count AOC were linearly related for both test bacteria, though data suggest that the P-17 bioluminescence assay requires more consistent luminescence monitoring. Bioluminescence results were obtained 2 or 3 days postinoculation, compared with 5 days for the ATP luminescence AOC assay and 8 days for the plate count assay. Plate count AOC assay results for nonmutant and bioluminescent bacteria from 36 water samples showed insignificant differences, indicating that the luminescent bacteria retained a full range of AOC measurement capability. This bioluminescence method is amenable to automation with a microplate format with programmable reagent injection.


Assuntos
Carbono/metabolismo , Medições Luminescentes , Compostos Orgânicos/metabolismo , Pseudomonas fluorescens/crescimento & desenvolvimento , Spirillum/crescimento & desenvolvimento , Microbiologia da Água , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Técnicas Bacteriológicas , Contagem de Colônia Microbiana , Elementos de DNA Transponíveis , Mutagênese Insercional , Óperon , Pseudomonas fluorescens/genética , Pseudomonas fluorescens/metabolismo , Sensibilidade e Especificidade , Spirillum/genética , Spirillum/metabolismo , Abastecimento de Água
16.
Mikrobiologiia ; 72(5): 600-8, 2003.
Artigo em Russo | MEDLINE | ID: mdl-14679896

RESUMO

The influence of oxygen availability during cultivation on the biosynthetic processes and enzymatic activities in the microaerophilic bacterium Spirillum winogradskii D-427 was studied, and the roles played by different systems of the defense against oxidation stress were determined. The metabolic adjustments caused by transition from microaerobic (2% O2) aerobic conditions (21% O2 of the gas phase) were found to slow down constructive metabolism and increase synthesis of exopolysaccharides as a means of external protection of cells from excess oxygen. This resulted in a twofold decline of the growth yield coefficient. Even though the low activity of catalase is compensated for by a multifold increase in the activities of other cytoplasmic enzymes protecting from toxic forms of O2--peroxidase and enzymes of the redox system of glutathione (glutathione peroxidase and glutathione reductase)--massive lysis of cells starts in the mid-exponential phase and leads to culture death in the stationary phase because of H2O2 accumulation in the periplasm (up to 10 micrograms/mg protein). The absence in cells of cytochrome-c-peroxidase, a periplasmic enzyme eliminating H2O2, was shown. It follows that the major cause of oxidative stress in cells is that active antioxidant defenses are located in the cytoplasm, whereas H2O2 accumulates in the periplasm due to the lack of cytochrome-c-peroxidase. The addition to the medium of thiosulfate promotes elimination of H2O2, stops cell lysis under aerobic conditions, lends stability to cultures, and results in a threefold increase in the growth yield.


Assuntos
Estresse Oxidativo , Spirillum/metabolismo , Aerobiose , Catalase/metabolismo , Meios de Cultura , Citocromo-c Peroxidase/metabolismo , Citoplasma/metabolismo , Glutationa Peroxidase/biossíntese , Glutationa Redutase/biossíntese , Peróxido de Hidrogênio/metabolismo , Periplasma/metabolismo , Polissacarídeos Bacterianos/biossíntese , Spirillum/crescimento & desenvolvimento , Tiossulfatos
17.
Genet. mol. biol ; 26(4): 537-543, dec. 2003. ilus, tab
Artigo em Inglês | LILACS | ID: lil-355300

RESUMO

Herbaspirillum spp. are endophytic diazotrophic bacteria associated with important agricultural crops. In this work, we analyzed six strains of H. seropedicae (Z78, M2, ZA69, ZA95, Z152, and Z67) and one strain of H. rubrisubalbicans (M4) by restriction fragment length polymorphism (RFLP) using HindIII or DraI restriction endonucleases, random amplified polymorphic DNA (RAPD), and partial sequencing of 16S rDNA. The results of these analyses ascribed the strains studied to three distinct groups: group I, consisting of M2 and M4; group II, of ZA69; and group III, of ZA95, Z78, Z67, and Z152. RAPD fingerprinting showed a higher variability than the other methods, and each strain had a unique electrophoretic pattern with five of the six primers used. Interestingly, H. seropedicae M2 was found by all analyses to be genetically very close to H. rubrisubalbicans M4. Our results show that RAPD can distinguish between all Herbaspirillum strains tested.


Assuntos
Polimorfismo de Fragmento de Restrição , Técnica de Amplificação ao Acaso de DNA Polimórfico , RNA Ribossômico , Spirillum , Meios de Cultura , Plantas
18.
Rofo ; 175(6): 830-4, 2003 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-12811697

RESUMO

PURPOSE: In vitro characterization of iron-containing bacterial particles (magnetosomes) as superparamagnetic contrast agents for MRI. MATERIAL AND METHODS: Different concentrations of magnetosomes were examined with a 1.5 T clinical whole-body MR system at 21 degrees C using the transit/receive extremity coil. Both longitudinal and transversal relaxivities (R1 and R2) of the magnetosomes were determined by an inversion recovery snapshot gradient recall echo (IR FLASH) with various inversion times and a multi echo spin echo sequence. Atomic absorption spectrometry (AAS) and electron microscopy were used as reference standard. RESULTS: Longitudinal and transverse relaxivities of the magnetosomes were calculated to be R1 = 7.688 mmol -1 s -1 and R2 = 147.67 mmol -1 s -1, respectively. The corresponding iron concentrations were determined in all dilutions using AAS, while the magnetosomes were morphologically delineated by electron microscopy. CONCLUSION: Magnetosomes represent a new and interesting class of iron-containing contrast agents warranting further evaluation in cellular cultures and animal models. Magnetosomes may be suited for displaying the vector distribution and gene expression of new molecular therapies.


Assuntos
Meios de Contraste , Compostos Férricos , Aumento da Imagem/métodos , Ferro , Imageamento por Ressonância Magnética/métodos , Óxidos , Spirillum , Relação Dose-Resposta a Droga , Compostos Férricos/análise , Óxido Ferroso-Férrico , Humanos , Ferro/análise , Microscopia Eletrônica , Óxidos/análise , Imagens de Fantasmas , Espectrofotometria Atômica
19.
Biophys J ; 84(5): 3379-88, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12719266

RESUMO

Atomic force microscopy was used to image Bdellovibrio bacteriovorus 109J, a gram-negative bacterial predator that consumes a variety of other gram-negative bacteria. In predator-prey communities grown on filters at hydrated air-solid interfaces, repeated cycles of hunting, invasion, growth, and lysis occurred readily even though the cells were limited to near two-dimensional movement. This system allowed us to image the bacteria directly without extensive preparation or modification, and many of the cells remained alive during imaging. Presented are images of the life cycle in two species of prey organisms, both Escherichia coli (a small prey bacterium that grows two-dimensionally on a surface) and Aquaspirillum serpens (a large prey bacterium that grows three-dimensionally on a surface), including high-resolution images of invaded prey cells called bdelloplasts. We obtained evidence for multiple invasions per prey cell, as well as significant heterogeneity in morphology of bdellovibrios. Mutant host-independent bdellovibrios were observed to have flagella and to excrete a coating that causes the predators to clump together on a surface. Most interestingly, changes in the texture of the cell surface membranes were measured during the course of the invasion cycle. Thus, coupled with our preparation method, atomic force microscopy allowed new observations to be made about Bdellovibrio at an interface. These studies raise important questions about the ways in which bacterial predation at interfaces (air-solid or liquid-solid) may be similar to or different from predation in solution.


Assuntos
Aderência Bacteriana/fisiologia , Bdellovibrio/fisiologia , Bdellovibrio/ultraestrutura , Ciclo Celular/fisiologia , Membrana Celular/ultraestrutura , Microscopia de Força Atômica/métodos , Bdellovibrio/crescimento & desenvolvimento , Bdellovibrio/patogenicidade , Adesão Celular/fisiologia , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/fisiologia , Escherichia coli/ultraestrutura , Interações Hospedeiro-Parasita/fisiologia , Dinâmica Populacional , Spirillum/crescimento & desenvolvimento , Spirillum/fisiologia , Spirillum/ultraestrutura , Propriedades de Superfície
20.
FEMS Microbiol Lett ; 212(2): 165-9, 2002 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-12113929

RESUMO

Phylogenetic analysis of 15 species of the genus Aquaspirillum based on 16S rRNA gene (rDNA) sequences indicated that the genus Aquaspirillum is phylogenetically heterogeneous and the species could be divided into four groups as follows: Aquaspirillum serpens, the type species of this genus, A. dispar and A. putridiconchylium are situated in the family Neisseriaceae; members of the second group, A. gracile, A. delicatum, A. anulus, A. giesbergeri, A. sinuosum, A. metamorphum and A. psychrophilum, are included in the family Comamonadaceae; the two members of the third group, A. arcticum and A. autotrophicum, are included in the family Oxalobacteriaceae; and members of the fourth group, A. polymorphum, A. peregrinum, and A. itersonii, are included in the alpha-subdivision of Proteobacteria. Thus, phylogenetic studies indicated that all the species excepting A. serpens, the type species, should be transferred to distinct genera.


Assuntos
RNA Ribossômico 16S/genética , Spirillum/classificação , Spirillum/genética , Água Doce/microbiologia , Variação Genética , Filogenia , Reação em Cadeia da Polimerase
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