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| Registros recuperados: 40 | |
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| Mancuso Nichols, Carol; Guezennec, Jean; Bowman, John. |
| Exopolysaccharides (EPSs) are high molecular weight carbohydrate polymers that make up a substantial component of the extracellular polymers surrounding most microbial cells in the marine environment. EPSs constitute a large fraction of the reduced carbon reservoir in the ocean and enhance the survival of marine bacteria by influencing the physicochemical environment around the bacterial cell. Microbial EPSs are abundant in the Antarctic marine environment, for example, in sea ice and ocean particles, where they may assist microbial communities to endure extremes of temperature, salinity, and nutrient availability. The microbial biodiversity of Antarctic ecosystems is relatively unexplored. Deep-sea hydrothermal vent environments are characterized by high... |
| Tipo: Text |
Palavras-chave: Ecosystems Hydrothermal Microbial; Polymers EPSs. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-624.pdf |
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| Petit, Anne-celine; Noiret, N; Sinquin, Corinne; Ratiskol, Jacqueline; Guezennec, Jean; Colliec-jouault, Sylvia. |
| Free-radical depolymerization with metallic catalysts has been investigated to depolymerize an exopolysaccharide (EPS), with a high molecular weight (> 10(6) g/Mol), produced by the bacterium Alteromonas macleodii subsp. fijiensis biovar deepsane. Three metals (copper, zinc and manganese) were used either alone or mixed. These metals led to the depolymerization of the high molecular weight bacterial polysaccharide with different efficiency. This study specifies some conditions required to produce, with good reproducibility and yield, EPS derivatives of reduced molecular weight ranging from 100,000 to 20,000 g/mol. The more influential parameters are specified. This is a first study to find suitable industrial conditions in the presence of these metallic... |
| Tipo: Text |
Palavras-chave: Bacterial exopolysaccharide; Free radical depolymerization; H202; Metal. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2146.pdf |
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| Guezennec, Jean; Chalkadiahis, Elefterios; Lerat, Etienne; Loubersac, Lionel. |
| This text which deals with the potential of the marine bacteria articulates around six chapters. The first one offers general points of view on marine wealth. The second gives a typology of the various valuations of the living matter in the form of biotechnologies. The third specifies the meaning of the marine or blue biotechnologies and places the part occupied by bacteria. The fourth describes several ways fur valuating bacteria and their by products (biopolymers as EPS and PHA) and applications and offer a digression on medicine coming from the sea. The fifth chapter is interested in the atypical environments and the particular conditions they offer. The sixth is dedicated to the New-Caledonian case, its natural specificities and introduces the case of... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00414/52540/53353.pdf |
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| Ortega Morales, Benjamín Otto; Santiago Garcia, J.l; Chan Bacab, M.j.; Moppert, Xavier; Miranda Tello, E; Fardeau, M.l.; Carrero, J.c.; Bartolo Perez, P.; Valadez Gonzalez, A; Guezennec, Jean. |
| Aims: This study was performed to determine the potential of tropical intertidal biofilm bacteria as a source of novel exopolymers (EPS). Methods and Results: A screening procedure was implemented to detect EPS-producing biofilm bacteria. Isolates MC3B-10 and MC6B-22, identified respectively as a Microbacterium species and Bacillus species by 16S rDNA and cellular fatty acids analyses, produced different EPS, as evidenced by colorimetric and gas chromatographic analyses. The polymer produced by isolate MC3B-10 displays significant surfactant activity, and may chelate calcium as evidenced by spectroscopic analysis. Conclusions: Polymer MC3B-10 appears to be a glycoprotein, while EPS MC6B-22 seems to be a true polysaccharide dominated by neutral sugars... |
| Tipo: Text |
Palavras-chave: Tropical intertidal biofilm bacteria; Surfactants; Microbacterium sp; Exopolymers; Bacillus sp; Anionic. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2530.pdf |
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| Simon-colin, Christelle; Raguenes, Gerard; Costa, Bernard; Guezennec, Jean. |
| The biosynthesis of poly-(3-hydroxyalkanoates) (PHAs) by Pseudomonas guezennei using glucose and/or fatty acids with chain-length from 3 to 18 carbon atoms as carbon sources was investigated. Glucose, acetate, pyruvate, propionate, valerate, hexanoate, heptanoate, octanoate, decanoate, and oleic acid were supplemented in the mineral medium as the sole carbon source or as a mixture for PHAs accumulation. Chemical composition of the resulting PHAs was analysed by coupled gas chromatography mass spectroscopy (GCMS), Fourier Transform Infrared Spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). PHAs contained up to 10 different types of 3-hydroxyalkanoic acid units, including saturated 3-hydroxyacids from C4 to C14, and unsaturated monomers... |
| Tipo: Text |
Palavras-chave: Carbon substrates; Pseudomonas guezennei; Polymer characterization; Polyhydroxyalkanoates. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6115.pdf |
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| Guezennec, Jean; Rimbault, A; Godfroy, Anne; Fromage, M; Marec, F; Rocchiocioli, F. |
| The existence of deep-sea hydrothermal thermophilic archaebacteria raises interesting questions about their metabolism and metabolic products both in a natural environment and in a culture medium. Moreover, the use of these microorganisms as a potential source of molecules of biotechnological interest must be considered, in the light of the fact that metabolic produits can enhance the risk of microbially-induced corrosion. Organic acids formed by an anaerobic thermophilic sulphur-dependent archaebacterium were analysed as tert-butyldimethylsilyl derivatives by GC and GC/MS. Data indicated the presence in significant amounts of propanoic, 2-methyl propanoic, 3-(methylthio) propanoic, phenylacetic and 4-hydroxyphenylacetic acids. In addition, the use of... |
| Tipo: Text |
Palavras-chave: ARCHAEA; ORGANIC ACIDS; AMINO ACIDS; LABELED ISOTOPES. |
| Ano: 1994 |
URL: http://archimer.ifremer.fr/doc/00099/21011/18637.pdf |
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| Nichols, Carol; Bowman, John; Guezennec, Jean. |
| The sea ice microbial community plays a key role in the productivity of the Southern Ocean. Exopolysaccharide (EPS) is a major component of the exopolymer secreted by many marine bacteria to enhance survival and is abundant in sea ice brine channels, but little is known about its function there. This study investigated the effects of temperature on EPS production in batch culture by CAM025, a marine bacterium isolated from sea ice sampled from the Southern Ocean. Previous studies have shown that CAM025 is a member of the genus Pseudoalteromonas and therefore belongs to a group found to be abundant in sea ice by culture-dependent and -independent techniques. Batch cultures were grown at -2 degrees C, 10 degrees C, and 20 degrees C, and cell number, optical... |
| Tipo: Text |
Palavras-chave: EPS yield; Psychrotolerant; Sea ice; Marine bacteria; Antarctica; Exopolymer; Exopolysaccharides. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-625.pdf |
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| Guezennec, Jean; Antoine, Elisabeth; Conte, Max. |
| In marine environments cathodic protection using sacrificial anodes or impressed current is widely used. In aerated seawater a cathodic potential of – 800 mV/SCE is generally accepted as efficient against marine corrosion. Biofilms formed on the metallic surfaces exposed to seawater can promote localized corrosion and interfere with the cathodic polarization process. Experiments were conducted both in natural environments and with a monoculture of a marine bacterium in order to understand the relationship between cathodic protection and biofilm formation. Results indicated that, in the former case, there was no evidence that biofilms significantly affect the cathodic current demand. Conversely, in sterilized seawater inoculated with a single bacterial... |
| Tipo: Text |
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| Ano: 1992 |
URL: https://archimer.ifremer.fr/doc/00480/59137/61765.pdf |
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| Cruz, Kimberly; Guezennec, Jean; Barkay, Tamar. |
| Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg... |
| Tipo: Text |
Palavras-chave: Mercury; Bacteria; Sorption; Tolerance; Exocellular polysaccharides. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00382/49348/49786.pdf |
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| Guezennec, Jean. |
| In contrast to the situation of a few years ago, the phenomenon of microbiologically induced corrosion is now generally accepted as being one of a number of mechanisms whereby corrosion occurs. A considerable amount of multi-disciplinary effort has been expended to determine the extent of the problem and to understand the phenomenon. Microbial corrosion refers to the degradation of metallic or non metallic structures resulting from the presence and the activity of a variety of organisms on the surfaces. Although, in many cases, microbial corrosion is closely associated with biofouling phenomena, the area in which it causes most damages concern the deterioration of metallic structures in soils and sediments with the well-known sulphate-reducing bacteria. |
| Tipo: Text |
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| Ano: 1990 |
URL: https://archimer.ifremer.fr/doc/00479/59106/61743.pdf |
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| Nichols, Carol Mancuso; Bowman, John; Guezennec, Jean. |
| A Gram-negative, aerobic, gliding, orange-yellow marine bacterium was isolated from particulate material sampled from the Southern Ocean. This strain produced an exopolysaccharide in liquid culture. 16S rRNA gene sequence analysis showed that this isolate was a member of the family Flavobacteriaceae, but represented a separate lineage. Major whole-cell fatty acids included i15:1 omega 10c, i15:0, beta-OH i15:0, a15:1 omega 10c, 15:0 and alpha-OH i15:0. The G+C content of the DNA was 49 mol%. Based on phylogenetic, phenotypic, chemotaxonomic and genotypic analyses, this bacterium was placed in a novel taxon as Olleya marilimosa gen. nov., sp. nov. with type strain CAM030(T) (=ACAM 1065(T)=CIP 108537(T)). |
| Tipo: Text |
Palavras-chave: Microbiology; Classification; Identification; Bacterie. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-457.pdf |
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| Pranal, V; Fiala Medioni, A; Guezennec, Jean. |
| Two deep-sea gastropods, Ifremeria nautilei and Alviniconcha hessleri, collected on a hydrothermal site of the North Fiji Basin (Southwestern Pacific) were analysed for polar and neutral lipids using gas-liquid chromatography/mass spectrometry. A high level of monounsaturated fatty acids (MUFAs) and a low level of omega 3 series polyunsaturated fatty acids (PUFAs) indicated that nutrition of both gastropods was related to a food web based mainly on bacterial supply. From differences in MUFA distribution between the 2 gastropods, it appeared that most of the energy requirements of A. hessleri were supplied by sulfur-oxidizing endobacteria whereas I. nautilei probably had a mixotrophic diet based on endogenous as well as exogenous bacteria. Given the... |
| Tipo: Text |
Palavras-chave: Hydrothermal vents; Gastropods; Chemosynthetic bacteria; Biomarkers; Fatty acids; Phospholipids; Neutral lipids. |
| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00282/39287/43133.pdf |
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| Chalkiadakis, Eletherios; Dufourcq, R.; Schmitt, Sophie; Brandily, Christophe; Kervarec, N.; Coatanea, Denis; Amir, H.; Loubersac, Lionel; Chanteau, S.; Guezennec, Jean; Dupont-rouzeyrol, M.; Simon-colin, Christelle. |
| Aims Exopolysaccharides (EPS) are industrially valuable molecules with numerous useful properties. This study describes the techniques used for the identification of a novel Vibrio bacterium and preliminary characterization of its EPS. Methods and Results Bioprospection in marine intertidal areas of New Caledonia followed by screening for EPS producing brought to selection of the isolate NC470. Phylogenetic analysis (biochemical tests, gene sequencing and DNADNA relatedness) permitted to identify NC470 as a new member of the Vibrio genus. The EPS was produced in batch fermentation, purified using the ultrafiltration process and analysed by colorimetry, Fourier Transform Infrared spectroscopy, gas chromatography, Nuclear Magnetic Resonance and HPLC-size... |
| Tipo: Text |
Palavras-chave: Biopolymers; Biotechnology; Exopolysaccharide; Fermentation biotechnology. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00144/25501/24036.pdf |
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| Senni, Karim; Gueniche, Farida; Foucault Bertaud, Alexandrine; Igondjo Tchen, Sylvie; Fioretti, Florence; Colliec-jouault, Sylvia; Durand, Patrick; Guezennec, Jean; Godeau, Gaston; Letourneur, Didier. |
| Fucoidans are sulfated fucosylated polymers from brown algae cell wall that exhibit some heparin/heparan sulfate properties. We previously demonstrated that these polysaccharides were able in vitro to stimulate dermal fibroblast proliferation and extracellular matrix deposition. Here, we investigated the action of a 16 kDa fucoidan fraction on parameters involved in connective tissue breakdown. This fucoidan is able to inhibit gelatinase A secretion and stromelysin 1 induction by interleukin-1 beta on dermal fibroblasts in culture. Furthermore, we observed that fucoidan increases the rate of association of MMPs with their specific inhibitors namely TIMPs. Using tissue sections of human skin in ex vivo experiments, we evidenced that this polysaccharide was... |
| Tipo: Text |
Palavras-chave: Interleukin 1 beta; Leukocyte elastase; Matrix metalloproteinases; Extracellular matrix remodeling; Glycosaminoglycans; Fucoidan. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2147.pdf |
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| Lemaitre, C.; Hernandez, G.; Béranger, G.; Guezennec, Jean. |
| By using electrochemical measurements and bacteria counting, we have verified that the added elements in an AISI 316L stainless steel, as poison allowing elements for the bacteria, like copper or arsenic, change the electrochemical properties versus the time, and modifie the structure of the bacterial population on the surface. Comparisons of the obtained results in synthetic sea water, sterilized or inoculated, and in natural sea water have permitted to observe very great differences versus the added elements. The use of sterilized natural sea water and then inoculated, gives results which permit to show the specific role of the aerobic and the anaerobic bacteria. |
| Tipo: Text |
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| Ano: 1990 |
URL: https://archimer.ifremer.fr/doc/00479/59107/61744.pdf |
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| Registros recuperados: 40 | |
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