Marine polysaccharides represent the most abundant and the most diverse marine biomass. These macromolécules are biosynthesized mainly by photosynthetic organisms (e.g. algae, micro-algae, cyanobacteria) and constitute a major main carbon source for heterotrophs organisms. Except glycoaminoglycans (e.g. heparin, chondroitin), terrestrial polysaccharides do not carry sulfate ester groups in contrast with marine polysaccharides. Thus the sulfation of polysaccharides other than glycosaminoglycans is considered as a necessary adaptation and a marker of marine origin. Marine polysaccharides are also very appreciated in industry for their physicochemical properties (e.g. agarose, carrageenans, alginates). Despite their ecological role, economical importance and their potential for applications, the extent of the structural diversity of marine polysaccharides is not known. During the last two decades, genome sequencing of marine organisms and of DNA from marine environmental samples (metagenomics) have generated a deluge of gene sequences; however, in contrast to terrestrial (meta)genomic investigations, the proportion of unknown protein families is higher in marine samples because oceans have been less studied so far. The functional interpretation of marine genomic and metagenomics data requires the prior functional characterization of genes/proteins to understand fundamental mechanisms encountered in marine environment such as organisms’ interactions, food-web, adaptation of populations to environmental change, etc. Interestingly, it was recently found that enzymes involved in the degradation of two marine polysaccharides (porphyran and cladophoran), were actually present in the human gut microbiota, suggesting that enzymes targeting other marine polysaccharides may be also found in this digestive system. The degradation of marine polysaccharides requires the concerted action of enzymes cocktails comprising complementary activities (GH: glycoside hydrolases, PL: polysaccharides lyases, sulfatases, etc). In the case of bacteria belonging to the phylum Bacteroidetes, genes involved in the polysaccharide degradation are clustered on the genome and co-regulated in “polysaccharides utilization loci” (PULs), each PUL targeting a specific glycan structure. Several PULs comprising GHs, PLs and sulfatases potentially targeting marine polysaccharides are predicted environmental Bacteroidetes and in Bacteroidetes from the human gut microbiome. However, the actual targets of these PULs are unknown in absence of experimental evidence for the function (specificity) of the encoded enzymes. We propose to systematically search and identify PUL putatively targeting marine polysaccharides in hundreds of genomes from sequence databanks as was already done for the PULs from 70 Bacteroidetes genomes from the human gut microbiota (www.cazy.org/PULDB). We will then select from marine and human gut Bacteroidetes about 50 PULs putatively targeting marine polysaccharides and which will represent approx. 500 genes encoding GHs, PLs, sulfatases, as well as proteins with unknown functions. All the proteins will be expressed recombinantly and will be biochemically characterized. At the end of the project we expect to have attributed the function to several marine PULs found in both marine organisms and in human gut microbiota. The results will directly impact the interpretation of marine genomic data and our understanding of the extent of the digestive abilities of the human gut microbiota.

Nanosizing electrode materials permit greatly improved ionic and electronic conductivities. Nevertheless, some challenges associated to the reactivity of nanomaterials remain due to their high specific surface area, which leads to parasitic and often irreversible reactions and strong interaction with electrolytes. To face these defies, Nano-INSPIRE is a fundamental project aiming at developing and studying the use of ionic liquids (ILs) to control the nano-structuration and to functionalize electrode nanomaterials surface in order to stabilize it. This project focuses on the stability of ILs coating layer in highly concentrated aqueous electrolyte depending on the ILs chemical composition and on the comprehension of its influence on the electrochemical performances. Sodium metal phosphate, which are among the most promising electrode materials for sodium-ion aqueous systems, will be used as reference materials.

Estuaries are highly productive environments where the transition from freshwater to saltwater leads to increased metal availability and accumulation in the sediment. As such, estuaries are strategic natural laboratories to study the interaction between biofilms, sediments, water and metals. Estuarine biofilms have abundance of exopolymeric substances (EPS), predominantly produced by diatoms and bacteria. The mucilaginous matrix of polymers supports attachment of microorganisms to the sediment, protecting them against desiccation and pollutants. Reactive groups allow binding of EPS to mineral surfaces and also have the potential to bind large quantities of metals. We recently found that EPS can be preserved at high concentrations several meters deep in estuarine sediments. Part of the estuarine EPS (i) may resist microbial and early diagenetic alterations and (ii) form organo-mineral complexes with metals and detrital clay minerals that potentially increase EPS preservation and metal binding. However, EPS-metal interactions are underexplored in subsurface sediments. Using sedimentary cores, EXODIA proposes to characterize the fate of EPS-metal complexes several meters below the sediment-water interface. The first objective of EXODIA is to understand microbial metabolisms related to EPS turnover in estuarine sediments. This will be achieved by characterizing the changes in sediment and porewater composition, microbial activity and EPS in function of depth. The second objective is to isolate and cultivate EPS producers and degraders from key sedimentary and/or geochemical interfaces. Following spectrometric or genomic identification, the representativeness of these isolates will be checked genotypically through a metabarcoding of the sedimentary microbial communities. Modifications of metal availability by reactive EPS could play a major role in clay mineral diagenesis. The third objective is to analyze the capacity of EPS extracted from sediments and of EPS produced in culture to form complexes with metals, ultimately leading to their precipitation. High-resolution microscopy and spectroscopy will allow to quantify and map metals and their speciation within EPS. We will measure the affinity of natural EPS and that from cultures for metals using e.g., calorimetry and titration experiments. Seven metal species will be investigated: Ca, Mg, Fe, Mn, Zn, Cd and Cu. The fourth objective is to characterize the transformations of EPS and minerals in forced diagenesis experiments reproducing the conditions encountered by the sediment during burial in a sedimentary basin. For the first time, EXODIA will monitor the evolution of EPS-metal-clay complexes in diagenetic conditions. Using high-pressure and high-temperature reactors, we expect to observe the precipitation of authigenic phases similar to the ones documented in ancient estuarine rocks. The fifth objective is to search for biosignatures of EPS-metal interactions in a collection of ancient estuarine sandstones of increasing age, burial and diagenesis. In ancient sandstones, we have documented several early diagenetic mineral phases, which could have precipitated following EPS-mineral-porewater reactions. EXODIA will look for remnants of EPS or EPS-metal interactions within e.g., clay coats, using high resolution techniques (e.g., SIMS). We propose to characterize modern EPS molecules and their degradation products through diagenesis experiments. This unique approach will guide our strategy for the exploration of ancient EPS molecules. To this aim, we will use innovative techniques that will enable us to work with very small quantities of material. The results of EXODIA could help to reconstruct EPS-metal biogeochemical cycles in modern and ancient estuaries, with potential applications in bioremediation.

The three-year ALALPHA project is an industrial research project combining the skills of an academic partner, the Bordeaux Institute of Condensed Matter Chemistry, with those of an industrial partner, SAFRAN. This project focuses on the development of alternative processes capable of obtaining the alpha phase of alumina (𝛼 - 𝐴𝑙2𝑂3) at low temperatures. Alumina is an engineered ceramic suitable for high performance applications in the defense and aerospace industries. The development of 𝛼-alumina coatings at low temperatures still remains a challenge. However, this would allow to answer one of the major challenges of the aerospace industry (military as well as civil) which is the lightening of structures and the reduction of costs, by the use of lighter alloys (even cheaper) in substitution of superalloys, for example. The primary benefit would be significant fuel savings with positive consequences on the environmental impact. With this in mind, SAFRAN, the world's leading aircraft engine manufacturer, is continually seeking to lighten its LEAP turbojet engine (an evolution of the CFM56, the engine powering the most aircraft in the world). Indeed, in the form of a dense layer deposited on a metal alloy, alumina 𝛼 is an effective protective barrier to the diffusion of oxygen particularly in low pressure turbines of turbojet engines. This project is concerned with obtaining a thick, adherent and dense coating of nanostructured 𝛼-alumina on various planar and complex shaped (ovoid type) metallic substrates, from a versatile and disruptive process based on the hydrothermal dehydration phenomenon at temperatures below 500 °C. The mechanical and temperature properties of this thick coating will be compared to those of a model thin coating, elaborated by the high power reactive magnetron sputtering process (R-HiPIMS). The main objectives of the ALALPHA project are to: 1) Design a new generation of cold-wall reactor to obtain nanostructured coatings composed of 100% alumina 𝛼, homogeneous in thickness for a process temperature below 500 °C, 2) Develop a model nanostructured coating of alumina 𝛼 by R-HiPIMS in the same temperature range, 3) Establish the relationships between process, microstructure and properties, and 4) Characterize the properties in terms of adhesion to different metal substrates as well as those of roughness, hardness and oxygen diffusion resistance. Whatever the process, the challenges will be to: 1) Obtain a nanostructured and single-phase 𝛼-alumina coating at low temperature, 2) Control its microstructure by understanding the different phenomena involved in relation to the process parameters, and 3) Coat metal substrates of different compositions while keeping similar adhesion and corrosion resistance properties. The project is organized in 6 strongly interacting tasks and will be carried out in 3 main steps. First, to design a reactor allowing to control both the temperature and the hydrodynamics (fluid flows) in the vicinity of the substrate to be coated. Second, optimize the process parameters to control the microstructure and thickness of the single-phase 𝛼-alumina coating. Third, characterize the different properties. The ALALPHA Project is part of the thematic axis 8 Materials with the themes "new processes" and "surface treatments and coatings, functionalization and smart coatings". It meets the priorities: a) Materials and thermal protection for extremely severe conditions and b) Corrosion control, surface engineering. The ALALPHA project is in the TRL range of 1 to 3.

In this project, we will use a combined experimental and theoretical approach in order to address three ambitious research topics. The common ground for these three sub-projects is the use of the highly reactive “Ni(diphosphine)” Ni(0) 14 electron fragment. The first sub-chapter addresses the current challenge of developing cross-coupling processes between C-sp3 (alkyl-halides) and organometallic compounds with first row transition metals. Preliminary results prove the Ni(diphosphine) fragment to be competent in such catalytic process, being the first example of its kind. The second project deals with the dehydrogenation of alkanes into alkenes using homogeneous catalysts. This very challenging task has never been reported with first row transition metal systems. Preliminary results indicate a stoichiometric transformation of the alkane by the above mentioned Ni fragment, opening the way for further improvements, and catalytic extension using different strategies (use of sacrificial alkene, use of tandem catalysis…). The third experimental project deals with CO2 functionalization. One of the originalities of our proposal is the design of the optimal Ni fragment for each process by theoretical calculations. This optimization step will only be possible after a comparison between experiments and theory for the known Ni(diphosphine) fragment.