Consulta: creatorFacets:"Guezennec, Jean"
Registros recuperados: 40
Data/hora: 08/06/2024 17:59:37

Bacterial exopolysaccharides from extreme marine environments with special consideration of the southern ocean, sea ice, and deep-sea hydrothermal vents: A review
Provedor de dados: 5
Autores: 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

Complement dependent cytotoxicity activity of therapeutic antibody fragments is acquired by immunogenic glycan coupling
Provedor de dados: 5
Autores: Courtois, Anthony; Gac Breton, Stephanie; Berthou, Christian; Guezennec, Jean; Bordron, Anne; Boisset, Claire.
Oligosaccharides are implicated in the development of the immune response notably in complement activation. Anti-tumoural immunotherapy by monoclonal antibodies (mAbs) offers some advantages to chemotherapy including cell targeting but some of them are inefficient to generate cytotoxicity dependent complement (CDC) known to be important in the antibody's efficacy. The aim of this study is to give a CDC activity of mAb by linkage of a complement activating oligosaccharide to this antibody via a hetero-bifunctional linker allowing control of the conjugation reaction. We worked on non Hodgkin Burkitt's lymphoma as cancer source, Fab fragments of rituximab devoid of complement activity as mAb and the trisaccharide Gal alpha(1 -&gt; 3)Gal beta(1 -&gt; 4)GlcNAc...
Tipo: Text
Palavras-chave: Complement system Gal alpha(1 -&gt; 3)Gal epitope immunogenic oligosaccharide immunotherapy non-Hodgkin lymphoma xenoantigen.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00125/23599/21423.pdf

Ultrasonic depolymerization of an exopolysaccharide produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid
Provedor de dados: 5
Autores: Petit, Anne-celine; Noiret, Nicolas; Guezennec, Jean; Gondrexon, N; Colliec-jouault, Sylvia.
Low frequency ultrasound was used to depolymerize a high-molecular-weight exopolysaccharide (EPS) produced by a deep-sea hydrothermal bacterium Alteromonas macleodii subsp. fijiensis biovar deepsane. The influence of several parameters was examined including the duration of ultrasonic irradiation, EPS concentration. reaction temperature and volume of the sonicated solution. With the aim of optimizing the depolyrnerization, the native EPS was simultaneously treated with hydrogen peroxide and ultrasound. This study identified the sonication conditions that produce low-molecular-weight derivatives from the native EPS (&gt;10(6) Da) with good reproducibility. (C) 2006 Elsevier B.V. All rights reserved.
Tipo: Text
Palavras-chave: Exopolysaccharide; Depolymerization; Ultrasound.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2123.pdf

Free-radical depolymerization with metallic catalysts of an exopolysaccharide produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid
Provedor de dados: 5
Autores: 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 (&gt; 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

Les biotechnologies bleues l’insoupçonnable potentiel de l’invisible. : le cas des bactéries marines.
Provedor de dados: 5
Autores: 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
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00414/52540/53353.pdf

Characterization of extracellular polymers synthesized by tropical intertidal biofilm bacteria
Provedor de dados: 5
Autores: 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

Study of biosorption of copper and silver by marine bacterial exopolysaccharides
Provedor de dados: 5
Autores: Deschatre, Marine; Ghillebaert, F.; Guezennec, Jean; Simon-colin, Christelle.
Metal bioremediation was studied by biosorption of analytical grade copper Cu(II) and silver Ag(I) by an exopolysaccharide (EPS) produced by marine bacteria from French Polynesia. Colorimetric analysis showed that EPS was composed of neutral sugars, uronic acids, acetate and especially high sulfate amount (29%). Metal biosorption experiments were conducted in batch process. Results showed that the maximum sorption capacities calculated according to Langmuir model were 400 mg g(-1) EPS (6.29 mmol g(-1)) and 256 mg g(-1) EPS (2.38 mmol g(-1)) for Cu(II) and Ag(I), respectively. The influence of pH, biosorbent concentration, ionic strength on EPS biosorption capacities was investigated. Results showed that bacterial EPS can be considered as very promising for...
Tipo: Text
Palavras-chave: Biosorption; Bacterial exopolysaccharides; Copper and silver removal; Bioremediation.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00601/71336/69766.pdf

Biosynthesis of medium chain length poly-3-hydroxyalkanoates by Pseudomonas guezennei from various carbon sources
Provedor de dados: 5
Autores: 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

Acides organiques produits par une archaébactérie anaérobie hyperthermophile soufre-dépendante
Provedor de dados: 5
Autores: 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

Effects of incubation temperature on growth and production of exopolysaccharides by an Antarctic sea ice bacterium grown in batch culture
Provedor de dados: 5
Autores: 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

Interaction protection cathodique et biofilm en milieu marin
Provedor de dados: 5
Autores: 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
Ano: 1992
URL: https://archimer.ifremer.fr/doc/00480/59137/61765.pdf

Sorption of Copper(II) and Silver(I) by Four Bacterial Exopolysaccharides
Provedor de dados: 5
Autores: Deschatre, Marine; Ghillebaert, F.; Guezennec, Jean; Simon-colin, Christelle.
Metal remediation was studied by the sorption of analytical grade copper Cu(II) and silver Ag(I) by four exopolysaccharides (EPS) produced by marine bacteria. Colorimetric analysis showed that these EPS were composed of neutral sugars, uronic acids (&gt;20 %), acetate, and sulfate (29 %). Metal sorption experiments were conducted in batch process. Results showed that the maximum sorption capacities calculated according to Langmuir model were 400 mg g−1 EPS (6.29 mmol g−1) and 333 mg g−1 EPS (3.09 mmol g−1) for Cu(II) and Ag(I), respectively. Optimum pH values of Ag(I) sorption were determined as 5.7. Experiment results also demonstrated the influence of initial silver concentration and EPS concentrations. Microanalyzing coupled with scanning electron...
Tipo: Text
Palavras-chave: Sorption; Bacterial exopolysaccharide; Copper and silver removal; Bioremediation.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00171/28222/27464.pdf

Production of exopolysaccharides by Antarctic marine bacterial isolates
Provedor de dados: 5
Autores: Nichols, C; Garon, Sandrine; Bowman, J; Raguenes, Gerard; Guezennec, Jean.
Aims: This study was undertaken to examine and characterize Antarctic marine bacterial isolates and the exopolysaccharides (EPS) they produce in laboratory culture.   Methods and Results: Two EPS-producing bacterial strains CAM025 and CAM036 were isolated from particulate material sampled from seawater and sea ice in the southern ocean. Analyses of 16S rDNA sequences placed these isolates in the genus Pseudoalteromonas. In batch culture, both strains produced EPS. The yield of EPS produced by CAM025 was 30-fold higher at -2 and 10degreesC than at 20degreesC. Crude chemical analyses showed that these EPS were composed primarily of neutral sugars and uronic acids with sulphates. Gas chromatographic analysis of monosaccharides confirmed these gross...
Tipo: Text
Palavras-chave: Sea ice; Pseudoalteromonas spp.; Particulate organic material; Exopolysaccharides; Antarctic marine bacteria.
Ano: 2004
URL: https://archimer.ifremer.fr/doc/2004/publication-629.pdf

Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance
Provedor de dados: 5
Autores: 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

La biocorrosion. Processus caractéristiques et moyens d’études
Provedor de dados: 5
Autores: 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
Ano: 1990
URL: https://archimer.ifremer.fr/doc/00479/59106/61743.pdf

Olleya marilimosa gen. nov., sp nov., an exopolysaccharide-producing marine bacterium from the family Flavobacteriaceae, isolated from the Southern Ocean
Provedor de dados: 5
Autores: 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

Fatty acid characteristics in two symbiotic gastropods from a deep hydrothermal vent of the west Pacific
Provedor de dados: 5
Autores: 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

Partial characterization of an exopolysaccharide secreted by a marine bacterium, Vibrio neocaledonicus sp nov., from New Caledonia
Provedor de dados: 5
Autores: 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

Fucoidan a sulfated polysaccharide from brown algae is a potent modulator of connective tissue proteolysis
Provedor de dados: 5
Autores: 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

Prévention de la biocorrosion des aciers inoxydables par modification de la composition chimique
Provedor de dados: 5
Autores: 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
Ano: 1990
URL: https://archimer.ifremer.fr/doc/00479/59107/61744.pdf

A di-O-dihydrogeranylgeranyl glycerol from Thermococus S 557, a novel ether lipid, and likely intermediate in the biosynthesis of diethers in Archaea
Provedor de dados: 5
Autores: 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

Floridoside extracted from the red alga Mastocarpus stellatus is a potent activator of the classical complement pathway
Provedor de dados: 5
Autores: Courtois, Anthony; Simon-colin, Christelle; Boisset, Claire; Berthou, Christian; Deslandes, Eric; Guezennec, Jean; Bordron, Anne.
Many biological properties of algae have been found to have useful applications in human health, particularly in the fields of oncology and immunology. Floridoside, extracted from the red alga Mastocarpus stellatus, has a structure similar to the xenoantigen Gal alpha 1-3 Gal. This xenoantigen has been described to induce a high immune response in human xenografts and is mediated by natural anti-gal antibodies that activate the classical complement pathway. Based on this property, we analyzed the potential activities of floridoside on the immune system. We demonstrated that floridoside activates a complement cascade via the classical complement pathway, through the recruitment and activation of natural IgM. This algal molecule could represent an important...
Tipo: Text
Palavras-chave: Complement system; Immunomodulation; Marine algae; Alpha galactosyl glycerol.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6248.pdf

Deep-sea genetic resources
Provedor de dados: 5
Autores: 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
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00153/26452/24558.pdf

Emulsifying Activity and Stability of a Non-Toxic Bioemulsifier Synthesized by Microbacterium sp MC3B-10
Provedor de dados: 5
Autores: 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

Exopolysaccharides Isolated from Hydrothermal Vent Bacteria Can Modulate the Complement System
Provedor de dados: 5
Autores: 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
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00198/30963/29337.pdf

Investigations into the uptake of copper, iron and selenium by a highly sulphated bacterial exopolysaccharide isolated from microbial mats
Provedor de dados: 5
Autores: Moppert, Xavier; Le Costaouec, Tinaig; Raguenes, Gerard; Courtois, Anthony; Simon-colin, Christelle; Crassous, Philippe; Costa, Bernard; Guezennec, Jean.
A bacterium isolated from microbial mats located on a polynesian atoll produced a high molecular weight (3,000 kDa) and highly sulphated exopolysaccharide. Previous studies showed that the chemical structure of this EPS consisted of neutral sugars, uronic acids, and high proportions of acetate and sulphate groups. The copper- and iron-binding ability of the purified pre-treated native EPS was investigated. Results showed that this EPS had a very high affinity for both copper (9.84 mmol g(-1) EPS) and ferrous iron (6.9 mmol g(-1) EPS). Amazingly, this EPS did not show any affinity for either ferric ions or selenium salts. This finding is one of the first steps in assessing the biotechnological potential of this polysaccharide.
Tipo: Text
Palavras-chave: Sulphated exopolysaccharide; Microbial mats; Iron; Copper; Binding capacity.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6397.pdf

A novel mcl-PHA produced on coprah oil by Pseudomonas guezennei biovar. tikehau, isolated from a "kopara" mat of French Polynesia
Provedor de dados: 5
Autores: 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

Biocorrosion des aciers en eau de mer naturelle, Conditions d’utilisation
Provedor de dados: 5
Autores: Lemoine, Lionel; Guezennec, Jean.
Tipo: Text
Ano: 1990
URL: https://archimer.ifremer.fr/doc/00479/59117/61747.pdf

Chemical characterization of exopolysaccharides from Antarctic marine bacteria
Provedor de dados: 5
Autores: 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

Emulsifying Activity and Stability of a Non-Toxic Bioemulsifier Synthesized by Microbacterium sp MC3B-10
Provedor de dados: 5
Autores: 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

Use of Natural Antimicrobial Peptides and Bacterial Biopolymers for Cultured Pearl Production
Provedor de dados: 5
Autores: Simon-colin, Christelle; Gueguen, Yannick; Bachere, Evelyne; Kouzayha, Achraf; Saulnier, Denis; Gayet, Nicolas; Guezennec, Jean.
Cultured pearls are the product of grafting and rearing of Pinctada margaritifera pearl oysters in their natural environment. Nucleus rejections and oyster mortality appear to result from bacterial infections or from an inappropriate grafting practice. To reduce the impact of bacterial infections, synthetic antibiotics have been applied during the grafting practice. However, the use of such antibiotics presents a number of problems associated with their incomplete biodegradability, limited efficacy in some cases, and an increased risk of selecting for antimicrobial resistant bacteria. We investigated the application of a marine antimicrobial peptide, tachyplesin, which is present in the Japanese horseshoe crab Tachypleus tridentatus, in combination with...
Tipo: Text
Palavras-chave: Pearl oyster; Exopolysaccharide; Tachyplesin; Antimicrobial.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00275/38599/37128.pdf

Exopolysaccharides produced by bacteria isolated from deep-sea hydrothermal vents: new agents with therapeutic potential
Provedor de dados: 5
Autores: 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

A novel mcl PHA-producing bacterium, Pseudomonas guezennei sp nov, isolated from a 'kopara' mat located in Rangiroa, an atoll of French Polynesia
Provedor de dados: 5
Autores: 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

Microbial mats in French Polynesia and their biotechnological applications
Provedor de dados: 5
Autores: Guezennec, Jean; Moppert, Xavier; Raguenes, Gerard; Richert, Laurent; Costa, Bernard; Simon-colin, Christelle.
It is well known that microorganisms well-adapted to survival in extreme ecosystems could be considered as new sources of biomolecules that have biotechnological importance. On French Polynesian atolls, microbial mats are developing in water ponds exposed to fluctuations in physical and chemical parameters. In these microbial mats, which are called "kopara" by the inhabitants, bacteria coexist with cyanobacteria, and a synergistic relationship may exist between these two types of living microorganisms. A large number of cyanobacteria and bacteria have been isolated from different mats. Under laboratory conditions, these microorganisms were shown to produce various exopolymers, including exopolysaccharides and poly-beta-hydroxyalkanoates, along with...
Tipo: Text
Palavras-chave: Microbial mats; Kopara; Biopolymers; Exopolysaccharides; Poly-beta-hydroxyalkanoates.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00029/14058/11423.pdf

Effect of an oversulfated exopolysaccharide on angiogenesis induced by fibroblast growth factor-2 or vascular endothelial growth factor in vitro
Provedor de dados: 5
Autores: 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

First steps of biofilm formation on stainless steels in natural seawater
Provedor de dados: 5
Autores: 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

Isolation and partial characterization of bacteria (Pseudoalteromonas sp.) with potential antibacterial activity from a marine costal environment from New Caledonia
Provedor de dados: 5
Autores: Dufourcq, R.; Chalkiadakis, Eletherios; Fauchon, M.; Deslandes, Eric; Kerjean, V.; Chanteau, S.; Petit, Elodie; Guezennec, Jean; Dupont-rouzeyrol, M.
Marine bacteria are a rich source of bioactive metabolites. However, the microbial diversity of marine ecosystem still needs to be explored. The aim of this study was to isolate and characterize bacteria with antimicrobial activities from various marine coastal environment of New Caledonia. We obtained 493 marine isolates from various environments and samples of which 63 (12.8%) presented an antibacterial activity against a panel of reference pathogenic strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis). Ten out of the most promising strains were cultured, fractionated and screened for antibacterial activity. Four of them (NC282, NC412, NC272 and NC120) showed at least an activity against reference and...
Tipo: Text
Palavras-chave: Antibacterial activity; Characterization; Marine bacteria; New Caledonia; Screening.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00174/28552/26994.pdf

Polysaccharide labelling: impact on structural and biological properties
Provedor de dados: 5
Autores: Roger, Olivier; Colliec-jouault, Sylvia; Ratiskol, Jacqueline; Sinquin, Corinne; Guezennec, Jean; Fischer, A; Chevolot, Lionel.
Three sulphated polysaccharides labelled at the reducing end with three different chemical treatments (2-aminopyridine (2-AP), 8-amino-1,3,6-trisulphonic acid (ANTS) and 6-(biotinyl)-aminocaproyl-hydrazide (BACH)) were compared. Molecular weight, chemical composition, nuclear magnetic resonance features and anticoagulant activity expressed as activated partial thromboplastin time were studied to determine whether structural and biological properties were retained or not after labelling. Partial depolymerisation and reduced biological activity were observed when reductive amination was performed with 2-AP. The initial properties were better retained with ANTS, and BACH did not modify the anticoagulant and structural properties. (C) 2002 Elsevier Science...
Tipo: Text
Palavras-chave: Anticoagulant activity; Reductive amination; Fluorescent tagging; Fucan; GAG; Sulphated polysaccharide.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-2113.pdf

Unusual Glycosaminoglycans from a Deep Sea Hydrothermal Bacterium Improve Fibrillar Collagen Structuring and Fibroblast Activities in Engineered Connective Tissues
Provedor de dados: 5
Autores: Senni, Karim; Gueniche, Farida; Changotade, Sylvie; Septier, Dominique; Sinquin, Corinne; Ratiskol, Jacqueline; Lutomski, Didier; Godeau, Gaston; Guezennec, Jean; Colliec-jouault, Sylvia.
Biopolymers produced by marine organisms can offer useful tools for regenerative medicine. Particularly, HE800 exopolysaccharide (HE800 EPS) secreted by a deep-sea hydrothermal bacterium displays an interesting glycosaminoglycan-like feature resembling hyaluronan. Previous studies demonstrated its effectiveness to enhance in vivo bone regeneration and to support osteoblastic cell metabolism in culture. Thus, in order to assess the usefulness of this high-molecular weight polymer in tissue engineering and tissue repair, in vitro reconstructed connective tissues containing HE800 EPS were performed. We showed that this polysaccharide promotes both collagen structuring and extracellular matrix settle by dermal fibroblasts. Furthermore, from the native HE800...
Tipo: Text
Palavras-chave: Marine hydrothermal bacteria; Glycosaminoglycan-mimetic; Collagen; Matrix metalloproteinases; Dermal fibroblast; Polysaccharides; Tissue engineering.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00138/24973/23072.pdf

Polar lipid fatty acids as indicators of trophic associations in a deep-sea vent system community
Provedor de dados: 5
Autores: Colaco, Ana; Desbruyeres, Daniel; Guezennec, Jean.
The polar lipid fatty acid (PLFA) profiles of invertebrates living in chemosynthetic communities can indicate the degree to which these animals depend on specific types of bacteria. To identify the nutritional sources of various species from deep-sea hydrothermal vents of the Mid-Atlantic Ridge, a Principal Component Analysis was performed using individual PLFA profiles as descriptors. Two associations representing different feeding groups were identified: (i) mussels, commensal polychaetes and gastropods, (ii) shrimps and crabs. The first association relies more on sulphide-oxidizing bacteria, while the second one has more anaerobic sulphate-reducing bacteria biomarkers. Other small invertebrates reveal different diets. The polychaete Amathys lutzi shows...
Tipo: Text
Palavras-chave: Mid Atlantic Ridge; Biomarkers; Hydrothermal vents; Fatty acids.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2538.pdf