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Modulation of the pharmacological effects of enzymatically-active PLA 2 by BTL-2, an isolectin isolated from the Bryothamnion triquetrum red alga

Oliveira, Simone C.B.; Fonseca, Fabiana V.; Antunes, Edson; Camargo, Enilton A.; Morganti, Rafael P.; Aparício, Ricardo; Toyama, Daniela O.; Beriam, Luís O.S.; Nunes, Eudismar V.; Cavada, Benildo S.; Nagano, Celso S.; Sampaio, Alexandre H.; Nascimento,
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
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467.96332%
Background. An interaction between lectins from marine algae and PLA 2 from rattlesnake was suggested some years ago. We, herein, studied the effects elicited by a small isolectin (BTL-2), isolated from Bryothamnion triquetrum, on the pharmacological and biological activities of a PLA 2 isolated from rattlesnake venom (Crotalus durissus cascavella), to better understand the enzymatic and pharmacological mechanisms of the PLA 2 and its complex. Results. This PLA2 consisted of 122 amino acids (approximate molecular mass of 14 kDa), its pI was estimated to be 8.3, and its amino acid sequence shared a high degree of similarity with that of other neurotoxic and enzymatically-active PLA2s. BTL-2 had a molecular mass estimated in approximately 9 kDa and was characterized as a basic protein. In addition, BTL-2 did not exhibit any enzymatic activity. The PLA2 and BTL-2 formed a stable heterodimer with a molecular mass of approximately 24-26 kDa, estimated by molecular exclusion HPLC. In the presence of BTL-2, we observed a significant increase in PLA2 activity, 23% higher than that of PLA2 alone. BTL-2 demonstrated an inhibition of 98% in the growth of the Gram-positive bacterial strain, Clavibacter michiganensis michiganensis (Cmm), but only 9.8% inhibition of the Gram-negative bacterial strain...

Rough virulent strain of Brucella ovis induces pro- and anti-inflammatory cytokines in reproductive tissues in experimentally infected rams

Antunes, João Marcelo Azevedo de Paula; Allendorf, Susan Dora; Appolinário, Camila Michele; Cagnini, Didier Quevedo; Figueiredo, Paula Ripamonte; Júnior, José Buratini; Baños, Joaquin Vicente; Kocan, Katherine M.; de la Fuente, José; Megid, Jane
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 339-343
ENG
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470.32805%
The ovine brucellosis caused by Brucella ovis has tropism for reproductive tissues but until now the mechanism of bacterial persistence is not understood. Cytokine expression profiles were studied for 8 months in rams after being experimentally infected with the rough virulent strain of B. ovis (R- B. ovis) to study the pathogenesis of B. ovis and immune mechanism possibly associated to bacteria tropism and persistence. The messenger RNA (mRNA) expression levels of interleukin-1α (IL-1α), IL-1β, IL-6, IL-10, IL-12, interferon-γ (INF-γ) and tumour necrosis factor-α (TNF-α) cytokines were quantified by real-time quantitative RT-PCR (qRT-PCR) in reproductive tissues (epididymus, testicles, ampolae, vesicular glands and bulbourethral glands), and non-reproductive (liver, spleen and kidneys) tissues at 30, 60, 120 and 240 days post infection (dpi). During the acute phase of infection at 30. dpi, the host immune response was most notable demonstrating an up-regulation of several cytokines in reproductive tissues, including the epididymus (IL-6, IL-1β and IL-1α), testicles (INF-γ and IL-12), bulbourethral glands (IL-6 and TNF-α) and ampolae (INF-γ, IL-10, IL-1β and IL-1α). During the development of infection, cytokine gene expression levels decreased...

Isolation and properties of a pure bacterial strain capable of fluorobenzene degradation as sole carbon and energy source

Carvalho, M. F.; Jorge, R. Ferreira; Pacheco, C. C.; Marco, P. De; Castro, P. M. L.
Fonte: Wiley Blackwell Publicador: Wiley Blackwell
Tipo: Artigo de Revista Científica
Publicado em //2005 ENG
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463.78953%
A pure bacterial strain capable of aerobic biodegradation of fluorobenzene (FB) as the sole carbon and energy source was isolated by selective enrichment from sediments collected from a polluted site. 16S rRNA and fatty acid analyses support that strain F11 belongs to a novel genus within the a-2 subgroup of the Proteobacteria, possibly within a new clade related to the order Rhizobiales. In batch cultures, growth of strain F11 on FB led to stoichiometric release of fluoride ion. Maximum experimental growth rate of 0.04 h-1 was obtained at FB concentration of 0.4 mM. Growth kinetics were described by the Luong model. An inhibitory effect with increasing FB concentrations was observed, with no growth occurring at concentrations higher than 3.9 mM. Strain F11 was shown to be able to use a range of other organic compounds, including other fluorinated compounds such as 2-fluorobenzoate, 4-fluorobenzoate and 4-fluorophenol. To our knowledge, this is the first time biodegradation of FB, as the sole carbon and energy source, by a pure bacterium has been reported.

Isolation of a Bacterial Strain with the Ability To Utilize the Sulfonated Azo Compound 4-Carboxy-4′-Sulfoazobenzene as the Sole Source of Carbon and Energy

Blümel, Silke; Contzen, Matthias; Lutz, Martina; Stolz, Andreas; Knackmuss, Hans-Joachim
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/1998 EN
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A bacterial strain (strain S5) which grows aerobically with the sulfonated azo compound 4-carboxy-4′-sulfoazobenzene as the sole source of carbon and energy was isolated. This strain was obtained by continuous adaptation of “Hydrogenophaga palleronii” S1, which has the ability to grow aerobically with 4-aminobenzenesulfonate. Strain S5 probably cleaves 4-carboxy-4′-sulfoazobenzene reductively under aerobic conditions to 4-aminobenzoate and 4-aminobenzene-sulfonate, which are mineralized by previously established degradation pathways.

Effect of Trimethoprim-Sulfamethoxazole on Recurrent Bacteriuria and Bacterial Persistence in Mice Infected with Uropathogenic Escherichia coli

Schilling, Joel D.; Lorenz, Robin G.; Hultgren, Scott J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2002 EN
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One of the more perplexing aspects of urinary tract infections (UTIs) is their high propensity to recur. It has been proposed that recurrent infections are a result of the reintroduction of bacteria from the gastrointestinal tract (GIT) to the urinary tract (UT); however, since a significant subset of recurrent UTIs are caused by an identical bacterial strain, it has been challenging to formally prove this hypothesis for same-strain recurrences by using epidemiologic approaches. We present data here obtained by using a mouse model of UTIs in which it was shown that 36% (5 of 14) of mice infected with uropathogenic Escherichia coli (UPEC) will have at least one bacteriuric recurrence, with 21% (3 of 14) having more than one recurrence during a 6-week period after an acute UTI. Intraurethrally infected mice develop UPEC reservoirs in both their feces and their bladders. Ten days of trimethoprim-sulfamethoxazole (SXT) therapy reduces urinary recurrences and eradicates fecal colonization, whereas 3 days of SXT treatment has no effect over a twenty-eight-day observation period despite clearing fecal colonization acutely. Interestingly, SXT is unable to eradicate bacteria from the bladder reservoir even after a 10-day treatment regimen, thus demonstrating that the bladder reservoir can persist even in the face of long-term antibiotic therapy.

Technique for Estimating Low Numbers of a Bacterial Strain(s) in Soil †

Makkar, N. S.; Casida, L. E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1987 EN
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455.81195%
A technique is described for obtaining most probable number estimates of the number of cells of a bacterial strain(s) when it is present in low numbers in the soil. The technique is based on the bacteriophage response that is elicited when a known number of bacteriophage for the bacterium of interest is incubated with soil dilutions in a nutrient broth. The technique was evaluated for use with gram-negative bacteria.

Isolation and Characterization of a Bacteriophage Tail-Like Bacteriocin from a Strain of Rhizobium

Lotz, Wolfgang; Mayer, Frank
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1972 EN
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466.2008%
Bacterial strain 16-3 spontaneously produces a bacteriocin which inhibits the growth of closely related strain 16-2. Both strains were newly isolated from root nodules of lupines and probably belong to the species Rhizobium lupini. Production of infectious progeny of newly isolated virulent phage 16-2-4 in strain 16-2 is inhibited completely if complexes are bacteriocin-treated during the first half of the latent period. Treatment begun during the second half leads to premature lysis of complexes and inactivates only those progeny phages which were not yet fully matured at the moment of the particle-induced lysis. Examination by electron microscope of the bacteriocin enrichment revealed the presence of particles 123 nm in length which resemble the tails of T-even bacteriophages. Since the particles sediment together with the bactericidal activity in the sucrose gradient and adsorb specifically to bacteriocin-sensitive cells, it is concluded that they are identical with the bactericidal agent. The particles are not found attached to phage heads and cannot self-propagate; they are regarded as incomplete and are named INCO particles. INCO particles consist of a core enveloped by a contractile sheath. One end of the sheath is connected to a baseplate to which six fibers...

Comparison of Biostimulation versus Bioaugmentation with Bacterial Strain PM1 for Treatment of Groundwater Contaminated with Methyl Tertiary Butyl Ether (MTBE)

Smith, Amanda E.; Hristova, Krassimira; Wood, Isaac; Mackay, Doug M.; Lory, Ernie; Lorenzana, Dale; Scow, Kate M.
Fonte: National Institue of Environmental Health Sciences Publicador: National Institue of Environmental Health Sciences
Tipo: Artigo de Revista Científica
EN
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Widespread contamination of groundwater by methyl tertiary butyl ether (MTBE) has triggered the exploration of different technologies for in situ removal of the pollutant, including biostimulation of naturally occurring microbial communities or bioaugmentation with specific microbial strains known to biodegrade the oxygenate. After laboratory studies revealed that bacterial strain PM1 rapidly and completely biodegraded MTBE in groundwater sediments, the organism was tested in an in situ field study at Port Hueneme Naval Construction Battalion Center in Oxnard, California. Two pilot test plots (A and B) in groundwater located down-gradient from an MTBE source were intermittently sparged with pure oxygen. Plot B was also inoculated with strain PM1. MTBE concentrations up-gradient from plots A and B initially varied temporally from 1.5 to 6 mg MTBE/L. Six months after treatment began, MTBE concentrations in monitoring wells down-gradient from the injection bed decreased substantially in the shallow zone of the ground-water in plots A and B, thus even in the absence of the inoculated strain PM1. In the deeper zone, downstream MTBE concentrations also decreased in plot A and to a lesser extent in plot B. Difficulties in delivery of oxygen to the deeper zone of plot B...

Direct and Indirect Effects of Protist Predation on Population Size Structure of a Bacterial Strain with High Phenotypic Plasticity

Corno, Gianluca; Jürgens, Klaus
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2006 EN
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459.8596%
We studied the impact of grazing and substrate supply on the size structure of a freshwater bacterial strain (Flectobacillus sp.) which showed pronounced morphological plasticity. The cell length varied from 2 to >40 μm and encompassed rods, curved cells, and long filaments. Without grazers and with a sufficient substrate supply, bacteria grew mainly in the form of medium-sized rods (4 to 7 μm), with a smaller proportion (<10%) of filamentous forms. Grazing experiments with the bacterivorous flagellate Ochromonas sp. showed that freely suspended cells of <7 μm were highly vulnerable to grazers, whereas filamentous cells were resistant to grazing and became enriched during predation. A comparison of long-term growth in carbon-limited chemostats with and without grazers revealed that strikingly different bacterial populations developed: treatments with flagellates were composed of >80% filamentous cells. These attained a biomass comparable to that of populations in chemostats without grazers, which were composed of medium-sized rods and c-shaped cells. Carbon starvation resulted in a fast decrease in cell length and a shift towards small rods, which were highly vulnerable to grazing. Dialysis bag experiments in combination with continuous cultivation revealed that filament formation was significantly enhanced even without direct contact of bacteria with bacterivores and was thus probably stimulated by grazer excretory products.

Regeneration of Phosphorus and Nitrogen by Four Species of Heterotrophic Nanoflagellates Feeding on Three Nutritional States of a Single Bacterial Strain

Eccleston-Parry, J. D.; Leadbeater, B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1995 EN
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463.78508%
Three physiological states of a single bacterial strain, namely, balanced, phosphorus-rich, and nitrogen-rich bacteria, were obtained by culturing a bacterial strain in chemostats under three different nutrient regimens. Each was shown to be distinctly different in elemental composition with respect to C/N/P ratio. These bacteria were fed to four species of heterotrophic nanoflagellates in batch culture grazing experiments, and the percent regeneration efficiencies of bacterium-bound nitrogen and phosphorus by the flagellates were compared. All flagellate species regenerated comparable amounts of nitrogen, which was thought to be due to their similar internal C/N ratios. There was, however, interspecies variation with regard to phosphorus regeneration: the two faster-growing species (Paraphysomonas imperforata and Bodo designis) released significantly more phosphorus than the two slower-growing species (Stephanoeca diplocostata and Jakoba libera). The observed differences were thought to have been influenced by a combination of life cycle strategies and internal C/P ratios.

Stenotrophomonas maltophilia SeITE02, a New Bacterial Strain Suitable for Bioremediation of Selenite-Contaminated Environmental Matrices▿

Antonioli, Paolo; Lampis, Silvia; Chesini, Irene; Vallini, Giovanni; Rinalducci, Sara; Zolla, Lello; Righetti, Pier Giorgio
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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462.15312%
Biochemical and proteomic tools have been utilized for investigating the mechanism of action of a new Stenotrophomonas maltophilia strain (SeITE02), a gammaproteobacterium capable of resistance to high concentrations of selenite [SeO32−, Se(IV)], reducing it to nontoxic elemental selenium under aerobic conditions; this strain was previously isolated from a selenite-contaminated mining soil. Biochemical analysis demonstrated that (i) nitrite reductase does not seem to take part in the process of selenite reduction by the bacterial strain SeITE02, although its involvement in this process had been hypothesized in other cases; (ii) nitrite strongly interferes with selenite removal when the two oxyanions (NO2− and SeO32−) are simultaneously present, suggesting that the two reduction/detoxification pathways share a common enzymatic step, probably at the level of cellular transport; (iii) in vitro, selenite reduction does not take place in the membrane or periplasmic fractions but only in the cytoplasm, where maximum activity is exhibited at pH 6.0 in the presence of NADPH; and (iv) glutathione is involved in the selenite reduction mechanism, since inhibition of its synthesis leads to a considerable delay in the onset of reduction. As far as the proteomic findings are concerned...

Identification of a bacterial strain isolated from the liver of a laboratory mouse as Microbacterium paraoxydans and emended description of the species Microbacterium paraoxydans Laffineur et al 2003

Buczolits, Sandra; Schumann, Peter; Valens, Maria; Rosselló-Mora, Ramón; Busse, Hans-Jürgen
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
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465.865%
A rod-shaped, Gram-positive bacterial strain, designated C57-33, was isolated from the liver of the laboratory mouse strain C57Bl/6J and characterised by a polyphasic approach. 16S rRNA gene sequence similarity placed strain C57-33 in the genus Microbacterium with Microbacterium paraoxydans CF36T as the next relative (99.9% sequence similarity). Major fatty acids ai-C15:0, i-C16:0 and ai-C17:0 and peptidoglycan type B2β with ornithine as the diagnostic cell-wall diamino acid and glycolyl residues were in agreement with the description of Microbacterium paraoxydans. The quinone system of C57-33 (major menaquinones MK-12 and MK-11) and polar lipid profile (major polar lipids diphosphatidyl glycerol, phosphatidyl glycerol and two unknown glycolipids) were in accordance with those of Microbacterium paraoxydans strains CF36T, CF7 and CF40 which were analysed in this study as well. The results of biochemical/physiological characterisation, DNA-DNA hybridization, MALDI-TOF mass spectrometry of cell extracts and comparison of protein patterns after SDS-PAGE demonstrated that our isolate C57-33 (= DSM 15461) is a strain of the species Microbacterium paraoxydans. Based on new characteristics such as quinone system, polar lipid profile and physiological traits analysed for strain C57-33...

Draft Genome Sequence of Bacillus subtilis QH-1, a Chromium-Reducing Bacterial Strain Isolated in Qinghai Province, China

Feng, Liang; Ma, Teng; Zhang, Junwen; Xu, Fen; Shi, Liu
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em 27/03/2014 EN
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Bacillus subtilis strain QH-1, a chromium-reducing bacterial strain, was isolated from a soil sample from a chromium-containing slag heap. The draft genome sequence of this bacterium is 4,034,036 bp in length, with a G+C content of 43.71%, and it is predicted to contain 4,082 protein-coding genes.

Draft Genome Sequence of a Xylanase-Producing Bacterial Strain, Cellvibrio mixtus J3-8

Wu, Yi-Rui; Lin, Bokun; Yu, Yuli
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em 11/12/2014 EN
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463.78508%
The xylanase-producing bacterial strain Cellvibrio mixtus J3-8 was isolated from grassland giant snails. The draft genome of strain J3-8 comprises 5,171,890 bp in 152 contigs with a G+C content of 46.66%. This is the first genome report about this bacterial species.

Identification of an Endophytic Antifungal Bacterial Strain Isolated from the Rubber Tree and Its Application in the Biological Control of Banana Fusarium Wilt

Tan, Deguan; Fu, Lili; Han, Bingyin; Sun, Xuepiao; Zheng, Peng; Zhang, Jiaming
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 02/07/2015 EN
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466.2008%
Banana Fusarium wilt (also known as Panama disease) is one of the most disastrous plant diseases. Effective control methods are still under exploring. The endophytic bacterial strain ITBB B5-1 was isolated from the rubber tree, and identified as Serratia marcescens by morphological, biochemical, and phylogenetic analyses. This strain exhibited a high potential for biological control against the banana Fusarium disease. Visual agar plate assay showed that ITBB B5-1 restricted the mycelial growth of the pathogenic fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4). Microscopic observation revealed that the cell wall of the FOC4 mycelium close to the co-cultured bacterium was partially decomposed, and the conidial formation was prohibited. The inhibition ratio of the culture fluid of ITBB B5-1 against the pathogenic fungus was 95.4% as estimated by tip culture assay. Chitinase and glucanase activity was detected in the culture fluid, and the highest activity was obtained at Day 2 and Day 3 of incubation for chitinase and glucanase, respectively. The filtrated cell-free culture fluid degraded the cell wall of FOC4 mycelium. These results indicated that chitinase and glucanase were involved in the antifungal mechanism of ITBB B5-1. The potted banana plants that were inoculated with ITBB B5-1 before infection with FOC4 showed 78.7% reduction in the disease severity index in the green house experiments. In the field trials...

Bacterial expression and purification of active hematopoietic cell kinase

Kristelly, R.; Qiu, W.; Gunn, N.; Scanlon, D.; Mulhern, T.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
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Src family kinases (SFKs) are traditionally purified from eukaryotic expression systems. These expression systems can be costly, yield heterogeneously phosphorylated protein samples and present difficulties when metabolic labeling is required for structural studies. Therefore, many attempts have been made to develop bacterial purification systems for SFKs. So far, high-yield bacterial expression systems have only been achieved for SFK kinase domains or for inactive mutants of constructs containing the regulatory SH3 and SH2 domains, but not for their active forms. Herein described is a bacterial expression system for the wild type, active SFK Hck containing SH3, SH2 and kinase domains. Hck plays an important role in phagocyte function as well as the etiology of chronic myeloid leukemia as Hck is an interaction partner of Bcr-Abl. Structural studies of Hck are essential to fully understand the signaling processes involved in host defense and leukemogenesis. Successful bacterial expression of Hck was possible by a dual strategy: (1) co-expression with YopH phosphatase in order to control host toxicity, and (2) expression in a bacterial strain that is RNase E deficient, which dramatically increased overall expression levels. The expressed Hck construct is unphosphorylated and appears to be in an open conformation. Bacterially expressed Hck is capable of autophosphorylation...

Immunological and Molecular Characterization of Susceptibility in Relationship to Bacterial Strain Differences in Mycobacterium avium subsp. paratuberculosis Infection in the Red Deer (Cervus elaphus)

O'Brien, R.; Mackintosh, C. G.; Bakker, D.; Kopecna, M.; Pavlik, I.; Griffin, J. F. T.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2006 EN
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464.9714%
Johne's disease (JD) infection, caused by Mycobacterium avium subsp. paratuberculosis, represents a major disease problem in farmed ruminants. Although JD has been well characterized in cattle and sheep, little is known of the infection dynamics or immunological response in deer. In this study, typing of M. avium subsp. paratuberculosis isolates from intestinal lymphatic tissues from 74 JD-infected animals showed that clinical isolates of M. avium subsp. paratuberculosis from New Zealand farmed red deer were exclusively of the bovine strain genotype. The susceptibility of deer to M. avium subsp. paratuberculosis was further investigated by experimental oral-route infection studies using defined isolates of virulent bovine and ovine M. avium subsp. paratuberculosis strains. Oral inoculation with high (109 CFU/animal) or medium (107 CFU/animal) doses of the bovine strain of M. avium subsp. paratuberculosis established 100% infection rates, compared to 69% infection following inoculation with a medium dose of the ovine strain. The high susceptibility of deer to the bovine strain of M. avium subsp. paratuberculosis was confirmed by a 50% infection rate following experimental inoculation with a low dose of bacteria (103 CFU/animal). This study is the first to report experimental M. avium subsp. paratuberculosis infection in red deer...

Bacterial cellulose: fabrication, characterization and biocompatibility studies

Zeng, Muling; Vallribera Massó, Adelina
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2014 ENG
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462.97316%
En marzo de 2011, apliqué a una beca del CSC (Consejo de Becas de China), en cooperación con la Universitat Autònoma de Barcelona (UAB). Después de medio año, conseguí la beca y comencé mi tesis doctoral bajo la supervisión de la Dra. Anna Roig y la Dra. Anna Laromaine. Mi proyecto asignada era en celulosa bacteriana: su síntesis, caracterización y estudios de biocompatibilidad. La celulosa bacteriana es un polisacárido de fuentes renovables, y puede ser producida por algunos tipos de bacterias en la naturaleza. Presenta propiedades químicas y físicas notables, incluyendo una alta pureza química y cristalinidad, una red de nanofibras, porosa, alta capacidad de absorción de agua y resistencia mecánica. La celulosa bacteriana se utiliza para una amplia variedad de aplicaciones comerciales. Por otra parte, la celulosa bacteriana es biocompatible con afinidad biológica y biodegradabilidad, que suscita la atención de investigadores en el área de la biomedicina. El primer objetivo de mi tesis fue aprender a producir películas de celulosa bacteriana y encontrar estrategias para controlar sus propiedades. Un segundo objetivo fue el desarrollo de métodos para la fabricación de nanocompuestos basedos con celulosa bacteriana. El objetivo final estudia la biocompatibilidad de las capas de celulosa bacteriana que hemos producido y su utilidad como soportes tridimensionales para el crecimiento celular. Así se pretende establecer una plataforma para el estudio de la interacción de células y nanopartículas en un entorno 3D más realista. Durante el primer año...

Nitrogen-regulated hypermutator strain of Synechococcus sp. for use in in vivo artificial evolution

Emlyn-Jones, Daniel; Price, Graeme (Dean); Andrews, Thomas
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
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463.78508%
Artificially evolved variants of proteins with roles in photosynthesis may be selected most conveniently by using a photosynthetic organism, such as a cyanobacterium, whose growth depends on the function of the target protein. However, the limited transformation efficiency of even the most transformable cyanobacteria wastes much of the diversity of mutant libraries of genes produced in vitro, impairing the coverage of sequence space. This highlights the advantages of an in vivo approach for generating diversity in the selection organism itself. We constructed two different hypermutator strains of Synechococcus sp. strain PCC 7942 by insertionally inactivating or nutritionally repressing the DNA mismatch repair gene, mutS. Inactivation of mutS greatly increases the mutation rate of the cyanobacterium's genes, leading to an up-to-300-fold increase in the frequency of resistance to the antibiotics rifampin and spectinomycin. In order to control the rate of mutation and to limit cellular damage resulting from prolonged hypermutation, we placed the uninterrupted mutS gene in the cyanobacterial chromosome under the transcriptional control of the cyanobacterial nirA promoter, which is repressed in the presence of NH4+ as an N source and derepressed in its absence. By removing or adding this substrate...

Bacterial tannases: production, properties and applications

Aguilar-Zárate,P.; Cruz-Hernández,M.A.; Montañez,J.C.; Belmares-Cerda,R.E.; Aguilar,C. N.
Fonte: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería Publicador: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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456.54375%
Tannins are polyphenolic compounds present in plants where they play an important role to prevent the attack of viruses, bacteria and fungi. Despite the fact that polyphenols inhibit the microbial growth, adaptation process has allowed developing mechanisms to transform them. One mechanism is the production of tannase, which has been obtained mostly from fungi. In recent years, some tannase producer bacteria have been isolated from different sources, mainly from animals and human intestine and feces as well as from fermented food and fruit wastes. Obtaining high titers of bacterial tannase depends mainly on the culture medium composition, the bacterial strain and the process optimization of culture conditions. This paper presents an overview of the recent investigations regarding the production, the physicochemical and molecular characteristics, the applications and the potential uses of bacterial tannases.