Incidence and risk factors of hypoxaemia after preoxygenation at induction of anaesthesia.

BACKGROUND: The incidence of hypoxaemia related to airway management is still a matter of concern. Our aim was to determine the factors that contribute to hypoxaemia during induction of anaesthesia after a standardised preoxygenation procedure. METHODS: The study was a multicentre and prospective observational trial. It evaluated the incidence of hypoxaemia at induction of anaesthesia in adult patients. The primary endpoint was the incidence of hypoxaemia defined as pulse oximetry of arterial oxyhaemoglobin saturation (SpO2) <95%. RESULTS: Of 2398 patients, hypoxaemia was observed in 158 (6.6%). We identified five preoperative independent risk factors: chronic obstructive pulmonary disease, hypertension, anticipated difficult mask ventilation and difficult tracheal intubation, and emergency surgery. There were also three pre-induction independent risk factors: difficult preoxygenation, difficult mask ventilation, and difficult tracheal intubation. We found a high negative predictive value of preoperative risk factors for difficult mask ventilation of 0.96 (0.95-0.96), and for difficult tracheal intubation (0.95 [0.94-0.96]). A total of 723 patients (30%) experienced difficult preoxygenation (FeO2 <90% at the end of preoxygenation). Male sex, chronic obstructive pulmonary disease, hypertension, emergency surgery, and predictable difficult mask ventilation were independent patient risk factors for difficult preoxygenation. CONCLUSIONS: Difficult mask ventilation and difficult tracheal intubation are risk factors for hypoxaemia at induction of general anaesthesia. Difficult preoxygenation was observed in 30% of patients and was also identified as a risk factor for hypoxaemia. This suggests that techniques improving preoxygenation should be implemented in daily practice.

Isolation and partial characterization of bacteria (Pseudoalteromonas sp.) with potential antibacterial activity from a marine costal environment from New Caledonia.

UNLABELLED: 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 multidrug-resistant pathogenic strains and were found to belong to the genus Pseudoalteromonas, according to the 16S phylogenetic analysis. The NC282 strain does not belong to any described Pseudoalteromonas species and might be of interest for further chemical and biological characterization. These findings suggest that the identified strains may contribute to the discovery for new sources of antimicrobial substances to develop new therapies to treat infections caused by multidrug-resistant bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: With the constant increasing of bacterial resistance against known antibiotics in worldwide public health, it is now necessary to find new sources of antimicrobials. Marine bacteria from New Caledonia were isolated, tested for antibacterial activity and characterized to find new active molecules against multidrug-resistant bacteria. This study illustrates the diversity of the marine ecosystem with potent new bacteria species. Also the potential of marine bacteria as a rich source of bioactive molecule, for example antibiotics, is highlighted.

Sorption of copper(II) and silver(I) by four bacterial exopolysaccharides.

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 (>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 microscopy demonstrated the presence of metal and morphological changes of the EPS by the sorption of metallic cations. The Fourier transform infrared spectroscopy analysis indicated possible functional groups (e.g., carboxyl, hydroxyl, and sulfate) of EPS involved in the metal sorption processes. These results showed that EPS from marine bacteria are very promising for copper and silver remediation. Further development in dynamic and continuous process at the industrial scale will be established next.

Partial characterization of an exopolysaccharide secreted by a marine bacterium, Vibrio neocaledonicus sp. nov., from New Caledonia.

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 DNA-DNA 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 exclusion chromatography. This EPS exhibits a high N-acetyl-hexosamines and uronic acid content with a low amount of neutral sugar. The molecular mass was 672 × 10(3)  Da. These data are relevant for possible technological exploitation. CONCLUSIONS: We propose the name Vibrio neocaledonicus sp. nov for this isolate NC470, producing an EPS with an unusual sugar composition. Comparison with other known polymers permitted to select applications for this polymer. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to evaluate the marine biodiversity of New Caledonia. It also highlights the biotechnological potential of New Caledonia marine bacteria.

Biosynthesis of medium chain length poly(3-hydroxyalkanoates) (mcl PHAs) from cosmetic co-products by Pseudomonas raguenesii sp. nov., isolated from Tetiaroa, French Polynesia.

A new bacterium, designated as strain TE9 was isolated from a microbial mat in French Polynesia and was studied for its ability to synthesize medium chain length poly-beta-hydroxyalkanoates (mcl PHAs) during cultivation on cosmetics co-products. The composition of PHAs was analysed by coupled gas chromatography mass spectroscopy (GC/MS), nuclear magnetic resonance (NMR) and Fourier Transform InfraRed (FTIR) spectroscopy. PHAs were composed of C6-C14 3-hydroxyacids monomers, with a predominance of 3-hydroxyoctanoate (3HO), 3-hydroxydecanoate (3HD) and 3-hydroxydodecanoate (3HDD). Differential scanning calorimetry (DSC) experiments allowed the characterization of elastomeric materials with a melting point T(m) near 50 degrees C, enthalpy of fusion DeltaH(m) from 27 to 32 J/g, and glass transition temperature T(g) of -43 degrees C. Molecular weights ranged from 175,000 to 358,000 g/mol. On the basis of the phenotypical features and genotypic investigations, strain TE9 was assigned to the Pseudomonas genus and the name of Pseudomonas raguenesii sp. nov. is proposed.

Halomonas profundus sp. nov., a new PHA-producing bacterium isolated from a deep-sea hydrothermal vent shrimp.

AIMS: The objective of the present work was to describe a new deep-sea, aerobic, mesophilic and heterotrophic bacterium, referenced as strain AT1214, able to produce polyhydroxyalkanoates (PHAs) under laboratory conditions. This bacterium was isolated from a shrimp collected nearby a hydrothermal vent located on the Mid-Atlantic Ridge. METHODS AND RESULTS: This micro-organism, on the basis of the phenotypical features and genotypic investigations, can be clearly assigned to the Halomonas genus and the name of Halomonas profundus is proposed. Optimal growth occurred between 32 and 37 degrees C at a pH between 8 and 9 and at ionic strength between 20 and 30 g l(-1) of sea salts. The G + C content of DNA was 58.6%. This bacterium produced PHAs of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from different carbon sources. CONCLUSIONS: The bacterium H. profundus produces PHA of 3HB and 3HV monomers from different carbon sources. SIGNIFICANCE AND IMPACT OF THE STUDY: PHAs share physical and material properties that suggest them for application in various areas, and are considered as an alternative to nonbiodegradable plastics produced from fossil oils. In this study, we describe a new bacteria isolated from a deep-sea hydrothermal vent with the capability to produce polyesters of biotechnological interest.

A novel mcl PHA-producing bacterium, Pseudomonas guezennei sp. nov., isolated from a 'kopara' mat located in Rangiroa, an atoll of French Polynesia.

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 l(-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 3-hydroxydecanaote (64 mol.%) and 3-hydroxyoctanoate (24 mol.%) (GC-MS, NMR) from a single nonrelated carbon substrate, i.e. glucose. CONCLUSIONS: The bacterium P. guezennei produces a novel PHA mcl with elastomeric properties. SIGNIFICANCE AND IMPACT OF THE STUDY: PHAs share physical and material properties that recommend them for application in various areas, and are considered as an alternative to nonbiodegradable plastics produced from fossil oils. In this study, we describe a new bacteria with the capability to synthesize a novel PHA with promising biotechnological applications.

Ultrasonic depolymerization of an exopolysaccharide produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid.

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 depolymerization, 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 (>10(6)Da) with good reproducibility.

Characterization of extracellular polymers synthesized by tropical intertidal biofilm bacteria.

AIM: 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 but with significant concentrations of uronic acids and hexosamines. EPS MC3B-10 possesses a higher surfactant activity than that of commercial surfactants, and given its anionic nature, may chelate cations thus proving useful in bioremediation. The chemical composition of polymer MC6B-22 suggests its potential biomedical application in tissue regeneration. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of a Microbacterium species producing EPS with surfactant properties, which expands our knowledge of the micro-organisms capable of producing these biomolecules. Furthermore, this work shows that tropical intertidal environments are a nonpreviously recognized habitat for bioprospecting EPS-producing bacteria, and that these molecules might be involved in ecological roles protecting the cells against dessication.

Bacterial exopolysaccharides from extreme marine environments with special consideration of the southern ocean, sea ice, and deep-sea hydrothermal vents: a review.

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 pressure, extreme temperature, and heavy metals. The commercial value of microbial EPSs from these habitats has been established recently. Extreme environments offer novel microbial biodiversity that produces varied and promising EPSs. The biotechnological potential of these biopolymers from hydrothermal vent environments as well as from Antarctic marine ecosystems remains largely untapped.

Production of exopolysaccharides by Antarctic marine bacterial isolates.

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 10 degrees C than at 20 degrees C. 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 compositional findings and molar ratios of monosaccharides revealed differences between the two EPS. CONCLUSIONS: The EPS produced by Antarctic bacterial isolates examined in this study appeared to be polyanionic and, therefore, 'sticky' with respect to cations such as trace metals. SIGNIFICANCE AND IMPACT OF THE STUDY: As the availability of iron as a trace metal is of critical importance in the southern ocean where it is know to limit primary production, the role of these bacterial EPS in the Antarctic marine environment has important ecological implications.

[Microbial polysaccharides of marine origin and their potential in human therapeutics]. / Les polysaccharides microbiens d'origine marine et leur potentiel en thérapeutique humaine.

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 heparin-like compounds. Unlike the native EPS, the resulting EPS presented anticoagulant properties as heparin. These EPS could provide biochemical entities with suitable functions for obtaining new drugs. They present original structural feature that can be modified to design compounds and improve their specificity.

Systemic effects on bone healing of a new hyaluronic acid-like bacterial exopolysaccharide.

Critical Size Defect (CSD) technique was used to evaluate the systemic activities on bone regeneration capacity of a newly discovered hyaluronic acid-like exopolysaccharide synthesized by a bacteria originating from a deep sea hydrothermal vent. Some systemic effects were previously detected on earlier experiments. A 5 mm diameter hole was made on each parietal bone of male rats. The right hole was filled with 0.5 mg of a new bacterial exopolysaccharide referenced HE 800, while the left hole remained free of any treatment. After 21 days, the holes and surrounding tissues were examined by direct examination, X-rays, and histological staining. Using HE 800, bone healing was almost complete after only 21 days in the treated hole and always complete in the control side by some systemic effect. Neovascularization was also observed along with an organized trabecular bone on both sides. No abnormal bone growth or conjunctival abnormalities were noticed. At the end of the experiment, 90.1% ( +/- 5.2) bone healing (n = 20) was observed on the treated side; conversely, the control side animals demonstrate an amazing healing 100% (+/- 0.5) by a systemic effect.

A new bone-healing material: a hyaluronic acid-like bacterial exopolysaccharide.

Critical size defect (CSD) technique was used to evaluate the bone regeneration capacity of a newly discovered hyaluronic acid-like exopolysaccharide synthesized by a bacteria originating from a deep sea hydrothermal vent. A 5 mm-diameter hole was made on each parietal bone of male rats. The right hole was filled with either a new bacterial exopolysaccharide referenced HE 800 or with collagen used as negative control, while the left hole remained free of any treatment. After 15 days, the holes and surrounding tissues were examined by direct examination, X-ray films, and histological staining. Using HE 800, bone healing was almost complete after only 15 days, with osteoblasts onto lying external bone surfaces and enhancing osteocyte inclusion. Neovascularization was also observed along with an organized trabecular bone. No abnormal bone growth or conjunctival abnormalities were noticed. At the end of the experiment, 95.9% (+/-6.2) bone healing (n = 20) was observed. Conversely, the collagen-treated animals did not demonstrate significant healing-17.8% (+/-18.1).

From extreme environments to biologically active exopolysaccharides.

In the course of the discovery of novel polysaccharides of biotechnological interest, it is now widely accepted that extremophilic microorganisms will provide a valuable resource not only for exploitation in novel biotechnological processes but also as models for investigating how biomolecules are stabilized when subjected to extreme conditions. Microbes isolated from extreme environments offer a great diversity in chemical and physical properties of their EPS as compared to anywhere else in the biosphere. Bacteria from remote areas still remain virtually unexplored and there is not doubt that extreme environments are a rich source of microorganisms of biotechnological importance. A number of interesting and unique bacterial polysaccharides have been isolated from these ecosystems and are expected to find applications in the very near future in different industrial. Further screenings are underway as well as research into understanding the structure-function relationships of these unusual polymers.

Deep-sea hydrothermal vents: a new source of innovative bacterial exopolysaccharides of biotechnological interest?

Polysaccharides and, in particular, microbial polysaccharides represent a class of important products of growing interest for many sectors of industry. Although many known marine bacteria produce exopolysaccharides (EPS), continuation in looking for new polysaccharide-producing microorganisms is promising. Hydrothermal deep-sea vents could be a source of novel EPS as indicated by the screening of a number of mesophilic heterotrophic bacteria recovered from different locations. Although originating from such extreme environment, some bacteria were shown to biosynthesize innovative EPS under laboratory conditions. Their specific rheological properties either in the presence or absence of monovalent and divalent ions, biological activities, metal binding capabilities, and novel chemical composition mean that these EPS are expected to find many applications in the near future.

A novel polymer produced by a bacterium isolated from a deep-sea hydrothermal vent polychaete annelid.

AIMS: The objective of the present work was to describe an aerobic, mesophilic and heterotrophic marine bacterium, designated HYD657, able to produce an exopolysaccharide (EPS). It was isolated from a East Pacific Rise deep-sea hydrothermal vent polychaete annelid. METHODS AND RESULTS: This micro-organism, on the basis of the phenotypical features and genotypic investigations, can be clearly assigned to the Alteromonas macleodii species and the name A. macleodii subsp. fijiensis biovar deepsane is proposed. Optimal growth occurs between 30 and 35 degrees C, at pH between 6.5 and 7.5 and at ionic strengths between 20 and 40 g x l(-1) NaCl. The G + C content of DNA was 46.5%. This bacterium excreted, under laboratory conditions, an EPS consisting of glucose, galactose, rhamnose, fucose and mannose as neutral sugars along with glucuronic and galacturonic acids and a diacidic hexose identified as a 3-0-(1 carboxyethyl)-D-glucuronic acid. Its average molecular mass was 1.6 x 10(6) Da. CONCLUSIONS: The bacterium HYD657, for which the name A. macleodii subsp. fijiensis biovar deepsane is proposed, produces an unusual EPS in specific medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to its interesting biological activities, applications have been found in cosmetics. Its probable contribution to the filamentous microbial mat in the Alvinella pompejana microenvironment can be also mentioned.

Microbial communities and exopolysaccharides from Polynesian mats.

Microbial mats present in two shallow atolls of French Polynesia were characterized by high amounts of exopolysaccharides associated with cyanobacteria as the predominating species. Cyanobacteria were found in the first centimeters of the gelatinous mats, whereas deeper layers showing the occurrence of the sulfate reducers Desulfovibrio and Desulfobacter species as determined by the presence of specific biomarkers. Exopolysaccharides were extracted from these mats and partially characterized. All fractions contained both neutral sugars and uronic acids with a predominance of the former. The large diversity in monosaccharides can be interpreted as the result of exopolymer biosynthesis by either different or unidentified cyanobacterial species.

Physical, chemical, and microbiological characteristics of microbial mats (kopara) in the South Pacific atolls of French Polynesia.

Microbial mats that develop in shallow brackish and hyposaline ponds in the rims of two French polynesian atolls (Rangiroa and Tetiaroa) were intensively investigated during the past three years. Comparative assessment of these mats (called kopara in polynesian language) showed remarkable similarities in their composition and structure. Due to the lack of iron, the color of the cyanobacterial pigments produced remained visible through the entire depth of the mats (20-40 cm depth), with alternate green, purple, and pink layers. Profiles of oxygen, sulfide, pH, and redox showed the anoxia of all mats from a depth of 2-3 mm. Analyses of bacterial pigments and bacterial lipids showed that all mats consisted of stratified layers of cyanobacteria (mainly Phormidium, Schizothrix, Scytonema) and purple and green phototrophic bacteria. The purple and green phototrophic bacteria cohabit with sulfate reducers (Desulfovibrio and Desulfobacter) and other heterotrophic bacteria. The microscopic bacterial determination emphasized the influence of salinity on the bacterial diversity, with higher diversity at low salinity, mainly for purple nonsulfur bacteria. Analyses of organic material and of exopolymers were also undertaken. Difference and similarities between mats from geomorphological, microbiological, and chemical points of view are discussed to provide multicriteria of classification of mats.