Use of Yeast Probiotics in Ruminants: Effects and Mechanisms of Action on Rumen pH, Fibre Degradation, and Microbiota According to the Diet

International audienc

Filière alternative de valorisation des Boues d'Hydroxydes poly-Métalliques (BHpM)

https://www.emse.fr/spip/IMG/pdf/Pollutec-perrin.pdfCommunications par affiche dans un congrès national : Poster, tremplin de la recherche au Sénat le 12 février 2008 Lauréat au tremplin de la recherche au Sénat le 12 février 200

Adsorption de PCB par des phases HDL organomodifiées

International audienceLes PCB sont des polluants persistants pour lesquels il faut encore chercher des solutions permettant de les retirer des sédiments. Le lavage par des tensioactifs offre de bons rendements de nettoyage. Il faut ensuite traiter les eaux du lessivage. Les Hydroxydes Doubles Lamellaires (HDL) ont montré des capacités intéressantes pour l'adsorption de polluants. L'insertion de tensioactifs lors de la synthèse de ces matériaux permet d'intercaler des polluants hydrophobes entre les feuillets brucitiques de ces argiles anioniques. Cette étude a pour objectif de tester la capacité de HDL à piéger un membre de la famille des PCB, le 4-chlorobiphényle (PCB 3). Les matériaux utilisés, à deux variantes du rapport MII/MIII, sont composés de zinc (Zn) et d'aluminium (Al) et intercalés avec du dodécylsulfate de sodium ou du dodécylbenzènesulfonate de sodium dès leur synthèse, ou encore des phases ZnAl-Chlore, mises en contact avec de l'acide humique après leur synthèse. Les HDL modifiés avec du tensioactifs montrent une forte capacité à la rétention du PCB 3, de l'ordre de 97% adsorbés, ainsi que les phases précipitées en présence du polluant. Les HDL sur lesquels est adsorbé l'acide humique montrent une capacité de dépollution de l'effluent bien inférieure, avec un maximum de 50% de PCB 3 adsorbés

Adsorption of Chromium (VI) by metal hydroxide sludge from the metal finishing

International audienceMetal finishing industries produce an important tonnage of metal hydroxide sludge (MHS) during the treatment of their liquid effluents charged with heavy metals. Generally, a small part of these sludge is valorized because of their important metal fickleness. Consequently, the majority of these metal hydroxide sludge is sent to landfill centers. We propose to valorize this sludge by using them as pollutant sorbent in order to retain the polluting species contained in the industrial aqueous effluents. The chosen pollutant for this preliminary study is Chromium (+VI). Starting from an experimental well defined protocol, various parameters have been studied (chemical nature of the sludge, solid/liquid ratio, concentration of the pollutant, particle size) in order to determine the experimental parameters which influence the sorption yield of these sludge and thus to validate the feasibility of an industrial application of this new way of valorisation. First results point out that the sorption yield is more than 95% independently from the experimental conditions. Moreover, experiments highlight that the sludge mass (and so sorbent sites) is THE only real parameter which influences the yield. In this article, a review of the patents on different aspects of the valorisation of polymetallic hydroxide sludge as pollutant trappers is presented

Mobility of organic pollutants in soil components. What role can magic angle spinning NMR play ?

International audienceThe adsorption-desorption mechanisms at the interface between organic and inorganic soil colloids influence the movement of pesticides and hence their bioavailability and biotransformation processes. Direct analyses of soils have been reported in the literature with the use of solid-state nuclear magnetic resonance (NMR) spectroscopy on dry samples. We recently demonstrated the potential of the 1H high resolution magic angle spinning (MAS) NMR technique to study such mechanisms in situ on highly hydrated samples. By using a well-characterized soil model, it was possible to distinguish the mobile and immobile pesticide unambiguously. In the present communication, a short review of MAS NMR techniques that allow covalent and non-covalent bond analysis is provided. The results obtained in our group on the adsorption of some pollutants such as phosphonomethylglycine (glyphosate), MCPA and 2-benzothiazole sulphonate are also presented. Specifically, we focus on the potential of MAS NMR spectroscopy for probing the behaviour (mobility) of these organic pollutants loaded onto the surface of different clays. The influence of clay hydration on NMR spectra has also been evaluate

Production of maltodextrin 1-Phosphate by Fibrobacter succinogenes S85

We show for the first time the occurrence of maltodextrin-1-Phosphate (MD-1P) (DP 2) in F. succinogenes S85, a rumen bacterium specialized in cellulolysis which is not able to use maltose and starch. MD-1P were found in intra and extracellular medium of resting cells incubated with glucose. We used 2D 1H NMR technique and TLC to identify their structure and quantify their production with time. It was also shown that these phosphorylated oligosaccharides originated both from exogenous glucose and endogenous glycoge

High-Density Protein Loading on Hierarchically Porous LDH-Aluminum Hydroxide Composites with a Rational Mesostructure

Hierarchically porous biocompatible Mg-Al-Cl type LDH composites containing aluminum hydroxide (Alhy) have been prepared using a phase-separation process. The sol-gel synthesis allows for the hierarchical pores of the LDH-Alhy composites to be tuned, leading to a high specific solid surface area per unit volume available for high molecular weight protein adsorptions. A linear relationship between effective surface area, SEFF, and loading capacity of a model protein, bovine serum albumin (BSA) is established following successful control of the structure of the LDH-Alhy composite. The threshold of mean pore diameter, Dpm, above which BSA is effectively adsorbed on the surface of LDH-Alhy composites, is deduced as 20 nm. In particular, LDH-Alhy composite aerogels obtained via supercritical drying exhibits extremely high capacity for protein loading (996 mg/g) due to a large mean mesopore diameter (> 30 nm). The protein loading on LDH-Alhy is >14 times that of a reference LDH material (70 mg/g) prepared via a standard procedure. Importantly, BSA molecules pre-adsorbed on porous composites were successfully released on soaking in ionic solutions (HPO42− and Cl− aq.). The superior capability of the biocompatible LDH materials for loading, encapsulation, and releasing large quantity of proteins was clearly demonstrated, which potential uses in separation and purification in addition to a high-capacity storage medium.The present work is supported by JSPS-MAE SAKURA program (N°34148TB).The present work is partially supported by JSPS KAKENHI, and by a research grant from the Foundation for the Promotion of Ion Engineering

Degradation of wheat straw by Fibrobacter succinogenes S85: a liquid and solid state Nuclear Magnetic resonance study

Wheat straw degradation by Fibrobacter succinogenes was monitored by nuclear magnetic resonance (NMR) spectroscopy and chemolytic methods to investigate the activity of an entire fibrolytic system on an intact complex substrate. In situ solid-state NMR with 13C cross-polarization magic angle spinning was used to monitor the modification of the composition and structure of lignocellulosic fibers (of 13C-enriched wheat straw) during the growth of bacteria on this substrate. There was no preferential degradation either of amorphous regions of cellulose versus crystalline regions or of cellulose versus hemicelluloses in wheat straw. This suggests either a simultaneous degradation of the amorphous and crystalline parts of cellulose and of cellulose and hemicelluloses by the enzymes or degradation at the surface at a molecular scale that cannot be detected by NMR. Liquid-state two-dimensional NMR experiments and chemolytic methods were used to analyze in detail the various sugars released into the culture medium. An integration of NMR signals enabled the quantification of oligosaccharides produced from wheat straw at various times of culture and showed the sequential activities of some of the fibrolytic enzymes of F. succinogenes S85 on wheat straw. In particular, acetylxylan esterase appeared to be more active than arabinofuranosidase, which was more active than -glucuronidase. Finally, cellodextrins did not accumulate to a great extent in the culture mediu

Experimental models to study intestinal microbes-mucus interactions in health and disease

A close symbiotic relationship exists between the intestinal microbiota and its host. A critical component of gut homeostasis is the presence of a mucus layer covering the gastrointestinal tract. Mucus is a viscoelastic gel at the interface between the luminal content and the host tissue that provides a habitat to the gut microbiota and protects the intestinal epithelium. The review starts by setting up the biological context underpinning the need for experimental models to study gut bacteria-mucus interactions in the digestive environment. We provide an overview of the structure and function of intestinal mucus and mucins, their interactions with intestinal bacteria (including commensal, probiotics and pathogenic microorganisms) and their role in modulating health and disease states. We then describe the characteristics and potentials of experimental models currently available to study the mechanisms underpinning the interaction of mucus with gut microbes, including in vitro, ex vivo and in vivo models. We then discuss the limitations and challenges facing this field of research

NMR study of cellulose and wheat straw degradation by Ruminococcus albus 20

Cellulose and wheat straw degradation by Ruminococcus albus was monitored using NMR spectroscopy. In situ solid-state 13C-cross-polarization magic angle spinning NMR was used to monitor the modification of the composition and structure of cellulose and 13C-enriched wheat straw during the growth of the bacterium on these substrates. In cellulose, amorphous regions were not preferentially degraded relative to crystalline areas by R. albus. Cellulose and hemicelluloses were also degraded at the same rate in wheat straw. Liquid state two-dimensional NMR experiments were used to analyse in detail the sugars released in the culture medium, and the integration of NMR signals enabled their quantification at various times of culture. The results showed glucose and cellodextrin accumulation in the medium of cellulose cultures; the cellodextrins were mainly cellotriose and accumulated to up to 2 mm after 4 days. In the wheat straw cultures, xylose was the main soluble sugar detected (1.4 mm); arabinose and glucose were also found, together with some oligosaccharides liberated from hemicellulose hydrolysis, but to a much lesser extent. No cellodextrins were detected. The results indicate that this strain of R. albus is unable to use glucose, xylose and arabinose for growth, but utilizes efficiently xylooligosaccharides. R. albus 20 appears to be less efficient than Fibrobacter succinogenes S85 for the degradation of wheat stra