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| Registros recuperados: 40 | |
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| Gonthier, Isabelle; Rager, Marie-noëlle; Metzger, Pierre; Guezennec, Jean; Largeau, Claude. |
| The lipids of a deep-sea hydrothermal vent arch ae on, Thermococcus S 557, were isolated, purified and structurally determined. Based on acid methanolysis and spectroscopic studies, the polar lipids were shown to comprise diphytanyl glycerol and dibiphytanyl diglycerol, typical membrane lipids of Arch aea. From the neutral lipids, 2,3-di-O-dihydro-14,15-geranylgeranyl glycerol was isolated. This novel ether lipid is, very likely, a close intermediate in the biosynthesis of diphytanyl glycerol diether in Arch aea. |
| Tipo: Text |
Palavras-chave: Mass spectrometry; NMR; Novel glycerol diether lipid; Thermococcus sp; Archaea. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-736.pdf |
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| Simon-colin, Christelle; Alain, Karine; Colin, Sebastien; Cozien, Joelle; Costa, B; Guezennec, Jean; Raguenes, Gerard. |
| Aims: The aim of the present study was to describe an aerobic, mesophilic and heterotrophic bacterium, designated RA26, able to produce a medium-chain-length polyhydroxyalkanoate (PHA). It was isolated from a French Polynesian bacterial mat located in the atoll of Rangiroa. Methods and Results: This micro-organism, on the basis of the phenotypical features and genotypic investigations can be clearly assigned to the Pseudomonas genus and the name of Pseudomonas guezennei is proposed. Optimal growth occurs between 33 and 37 degrees C, at a pH between 6 4 and 7 1 and at ionic strength of 15 g 1(-1) of sea salts. The G+C content of DNA is 63.2%. Under laboratory conditions, this bacterium produced a novel, medium-chain-length PHA, mainly composed of... |
| Tipo: Text |
Palavras-chave: Pseudomonas; Polyhydroxyalkanaote; Microbial mat; Kopara. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3858.pdf |
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| Simon-colin, Christelle; Raguenes, Gerard; Crassous, Philippe; Moppert, X; Guezennec, Jean. |
| Pseudomonasguezennei biovar. tikehau was isolated from a microbial mat on the atoll of Tikehau in French Polynesia, and is able to synthesize medium chain length poly-beta-hydroxyalkanaote copolymers when grown on coprah oil. A two-step cultivation process was used and the biosynthesis of PHAs was followed along 52 h by regular culture sampling. The polyester was purified from freeze-dried cells and analysed by nuclear magnetic resonance (NMR), Fourier transform infra red (FTIR), and gas chromatography mass spectrometries. The copolyester produced by P. guezennei biovar. tikehau from coprah oil mainly consisted of saturated monomers, i.e. 3-hydroxyoctanoate (3HO) and 3-hydroxydecanoate (3HD), and the monomeric composition of the polyester did not change... |
| Tipo: Text |
Palavras-chave: Polyhydroxyalkanaote; PHAs; Pseudomonas; "kopara"; Microbial mat. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6119.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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| 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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| 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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| 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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| 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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| Nichols, Carol; Lardiere, Sandrine; Bowman, John; Nichols, Peter; Gibson, John; Guezennec, Jean. |
| Exopolysaccharides (EPS) may have an important role in the Antarctic marine environment, possibly acting as ligands for trace metal nutrients such as iron or providing cryoprotection for growth at low temperature and high salinity. Ten bacterial strains, isolated from Southern Ocean particulate material or from sea ice, were characterized. Whole cell fatty acid profiles and 16S rRNA gene sequences showed that the isolates included representatives of the genera Pseudoalteromonas, Shewanella, Polaribacter, and Flavobacterium as well as one strain, which constituted a new bacterial genus in the family Flavobacteriaceae. The isolates are, therefore, members of the "Gammaproteobacteria" and Cytophaga-Flexibacter-Bacteroides, the taxonomic groups that have been... |
| Tipo: Text |
Palavras-chave: Marine particulates; Sea ice; Marine bacteria; Antarctica; Exopolysaccharides. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-623.pdf |
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| Desbruyere, D; Arnaud-haond, Sophie; Fabri, Marie-claire; Guezennec, Jean; Querellou, Joel. |
| Two third of our Planet are covered by oceans more than 3,000m deep (~ 307 millions km2) and the mean depth of the sea is approximately 3,800m. The volume of the deep ocean (aphotic) is about 1,280 Millions of km3 while the volume of terrestrial ecosystems is only 125 Millions of km3. Therefore, the deep-sea ecosystem is by far the largest complex biome on the Earth. However, it suffers from a general disinterest of the public and decision makers due to its remoteness and inaccessibility. Edward Forbes "azoic theory" is still deeply rooted in most people brains and during public conferences, a large part of the audience being still amazed to hear that macroscopic life does exist in the deepest part of the sea floor (11,000m depth). |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00153/26452/24558.pdf |
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| Matou, Sabine; Colliec-jouault, Sylvia; Galy Fauroux, Isabelle; Ratiskol, Jacqueline; Sinquin, Corinne; Guezennec, Jean; Fischer, Anne-marie; Helley, Dominique. |
| The aim of this study was to determine the angiogenic properties of an oversulfated exopolysaccharide (OS-EPS) derived from a polysaccharide secreted by the mesophilic bacterium Alteromonas infernus. We compared the effect of this OS-EPS with that of a non-oversulfated exopolysaccharide (EPS) on human umbilical vein endothelial cell (HUVEC) proliferation, migration and differentiation induced by basic fibroblast growth factor (FGF-2) or vascular endothelial growth factor (VEGF). OS-EPS enhanced HUVEC proliferation by 58% when used alone, and by respectively 30% and 70% in the presence of FGF-2 and VEGF. OS-EPS also increased the density of tubular structures on Matrigel in the presence of FGF-2 or VEGF. Vascular tube fort-nation was related to alpha(6)... |
| Tipo: Text |
Palavras-chave: Matrigel; Collagen gel; Alpha 6 integrin subunit; Angiogenic growth factor; Polysaccharide; Angiogenesis. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-2118.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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| Camacho-chab, Juan Carlos; Guezennec, Jean; Chan-bacab, Manuel Jesus; Rios-leal, Elvira; Sinquin, Corinne; Muniz-salazar, Raquel; De La Rosa-garcia, Susana Del C.; Reyes-estebanez, Manuela; Ortega-morales, Benjamin Otto. |
| A previously reported bacterial bioemulsifier, here termed microbactan, was further analyzed to characterize its lipid component, molecular weight, ionic character and toxicity, along with its bioemulsifying potential for hydrophobic substrates at a range of temperatures, salinities and pH values. Analyses showed that microbactan is a high molecular weight (700 kDa), non-ionic molecule. Gas chromatography of the lipid fraction revealed the presence of palmitic, stearic, and oleic acids; thus microbactan may be considered a glycolipoprotein. Microbactan emulsified aromatic hydrocarbons and oils to various extents; the highest emulsification index was recorded against motor oil (96%). The stability of the microbactan-motor oil emulsion model reached its... |
| Tipo: Text |
Palavras-chave: Bioemulsifier; Emulsifying stability; Non-toxic; Microbacterium sp; Biotechnology. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00171/28260/26530.pdf |
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| Camacho-chab, Juan Carlos; Guezennec, Jean; Chan-bacab, Manuel Jesus; Rios-leal, Elvira; Sinquin, Corinne; Muniz-salazar, Raquel; De La Rosa-garcia, Susana Del C.; Reyes-estebanez, Manuela; Ortega-morales, Benjamin Otto. |
| A previously reported bacterial bioemulsifier, here termed microbactan, was further analyzed to characterize its lipid component, molecular weight, ionic character and toxicity, along with its bioemulsifying potential for hydrophobic substrates at a range of temperatures, salinities and pH values. Analyses showed that microbactan is a high molecular weight (700 kDa), non-ionic molecule. Gas chromatography of the lipid fraction revealed the presence of palmitic, stearic, and oleic acids; thus microbactan may be considered a glycolipoprotein. Microbactan emulsified aromatic hydrocarbons and oils to various extents; the highest emulsification index was recorded against motor oil (96%). The stability of the microbactan-motor oil emulsion model reached its... |
| Tipo: Text |
Palavras-chave: Bioemulsifier; Emulsifying stability; Non-toxic; Microbacterium sp; Biotechnology. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00372/48356/48545.pdf |
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| Courtois, Anthony; Berthou, Christian; Guezennec, Jean; Boisset, Claire; Bordron, Anne. |
| The complement system is involved in the defence against bacterial infection, or in the elimination of tumour cells. However, disturbances in this system contributes to the pathogenesis of various inflammatory diseases. The efficiency of therapeutic anti-tumour antibodies is enhanced when the complement system is stimulated. In contrast, cancer cells are able to inhibit the complement system and thus proliferate. Some marine molecules are currently being developed as new drugs for use in humans. Among them, known exopolyssacharides (EPSs) generally originate from fungi, but few studies have been performed on bacterial EPSs and even fewer on EPSs extracted from deep-sea hydrothermal vent microbes. For use in humans, these high molecular weight EPSs must be... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00198/30963/29337.pdf |
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| Colliec-jouault, Sylvia; Zanchetta, P; Helley, D; Ratiskol, Jacqueline; Sinquin, Corinne; Fischer, A. M.; Guezennec, Jean. |
| Bacterial polysaccharides offer fascinating potential applications for the pharmaceutical industry. Although many known marine bacteria produce exopolysaccharides (EPS), continuation in looking for new polysaccharide-producing micro-organisms is promising. Marine bacteria, isolated from deep-sea hydrothermal vents, have demonstrated their ability to produce in aerobic conditions, unusual EPS. With the aim of discovering biological activities, EPS presenting different structural features were studied. An EPS secreted by Vibrio, diabolicus was evaluated on the restoration of bone integrity in experimental model and was demonstrated to be a strong bone-healing material. Another EPS produced by Alteromonas infernus was modified in order to obtain new... |
| Tipo: Text |
Palavras-chave: Hydrothermal vents; Exopolysaccharides; Bone healing; Biomimetic; Anticoagulant activity; Sources hydrothermales; Exopolysaccharide; Cicatrisation osseuse; Biomimétique; Activité anticoagulante. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-2117.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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| Bellon-fontaine, M.-n.; Bertrand, P; Compere, Chantal; Costa, D; Guezennec, Jean; Marcus, P; Poleunis, C.; Pradier, C.-m.; Rondot, B; Walls, M.g.. |
| Numerous works are reported in literature concerning the biofilm growth on surfaces in seawater but the understanding of the adhesion mechanisms in the first steps of immersion is still subject to investigations. A knowledge of the chemical composition and of the kinetics of conditioning layer formation is a central requirement for a sound scientific understanding of biofilm growth. Due to its complexity and to the interdisciplinary nature of the subject, this research asks for the collaboration between the fields of material science, surface analyses, chemistry, marine microbiology and biochemistry. The first steps of biofilm formation on 316L stainless steels immersed in natural sea water have been studied, using a broad range of surface characterisation... |
| Tipo: Text |
Palavras-chave: Sea water; Substrates; Biofilm. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/1998/acte-1699.pdf |
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| Registros recuperados: 40 | |
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