Challenges in microbial ecology: building predictive understanding of community function and dynamics.

The importance of microbial communities (MCs) cannot be overstated. MCs underpin the biogeochemical cycles of the earth's soil, oceans and the atmosphere, and perform ecosystem functions that impact plants, animals and humans. Yet our ability to predict and manage the function of these highly complex, dynamically changing communities is limited. Building predictive models that link MC composition to function is a key emerging challenge in microbial ecology. Here, we argue that addressing this challenge requires close coordination of experimental data collection and method development with mathematical model building. We discuss specific examples where model-experiment integration has already resulted in important insights into MC function and structure. We also highlight key research questions that still demand better integration of experiments and models. We argue that such integration is needed to achieve significant progress in our understanding of MC dynamics and function, and we make specific practical suggestions as to how this could be achieved

Ecoconception d'un procédé innovant pour la production de molécules à forte valeur ajoutée

SETAC Europe LCA case study symposium, Montpellier, FRA, 20-/09/2016 - 22/09/2016International audienceComparative LCA of bioethanol production from waste and from beets.ACV comparative de la production de bioéthanol à partir de déchets et bioéthanol à partir de betteraves

Eco-conception d'un procédé de production de bio-molécules par électrosynthèse microbienne à partir de déchets organiques

International audienceReplacing raw materials by secondary materials is a current issue and the use of waste or, better still; “bio-waste” (biodegradable green space residues, food and kitchen waste) is a promising way to do it. Producing energy from bio-waste is relatively known especially thanks to anaerobic digestion (AD) process which produces a biogas but producing chemicals is quite more technically complex. The BIORARE project (financed by the French National Research Agency – Investments for the future” call) has been aspired to provide an environmentally relevant solution to produce chemicals from bio-waste. The challenge of BIORARE project is a synergy between an innovative technology (microbial electrosynthesis process, also called bioelectrosynthesis (BES)) and a waste management option (AD plant). The AD plant provides renewable electricity from biogas burning and volatile fatty acids (VFAs) from bio-waste hydrolysis which are both send to the BES. In the BES, microorganisms convert VFAs into chemicals. This coupling technology, called BIORARE concept, has a low TRL (4) and needs to be driven by technical and environmental strategies. The Life Cycle Assessment methodology was chosen to eco-design the BIORARE concept based on expert’s opinion and prior experimentations. Performing LCA on such a low TRL concept was based on core issues all along the LCA methodology. The first question is what the function is. We assume a theoretical production of two types of chemicals: bioethanol or succinic acid thanks to BES and a waste treatment thanks to AD. The second question is what the scenarios for the comparison are. Two types of scenarios were built-up: a business as usual (BAU) scenario and a transition scenario (with the BES but using a simpler substrate than bio-waste: water). The next issue was to model and quantify theoretical synergies throughout the whole system. Synergies help reducing the use of external resources and could be achieved since AD allows the production of required input of the BES such as energy through biogas combustion, VFAs and CO2 via waste hydrolysis. Since no BES coupled with anaerobic digestion exists at pilot scale, the calculation approach to model these synergies has progressed with the upgraded skills and knowledge during the project. To identify the key parameters or synergies, sensitivity analyses have been carried out for the BES design and operating conditions. The LCIA showed that the BIORARE concept is environmentally competitive compared to the BAU and transition scenarios regarding the theoretical production of bioethanol or succinic acid. The results highlight the influence of current density on energy efficiency of the BES, and the hydrolysis rate to provide sufficient VFAs to the BES. In other words, we managed to model a low TRL industrial symbiosis through an eco-design approach based on LCA methodology aiming different potential chemical markets

Ecoconception d'un procédé innovant pour la production de molécules à forte valeur ajoutée

SETAC Europe LCA case study symposium, Montpellier, FRA, 20-/09/2016 - 22/09/2016International audienceComparative LCA of bioethanol production from waste and from beets.ACV comparative de la production de bioéthanol à partir de déchets et bioéthanol à partir de betteraves

Bioflocculation and settling studies of native wastewater filamentous cyanobacteria using different cultivation systems for a low-cost and easy to control harvesting process

Bioflocculation phenomena for filamentous cyanobacteria were studied and analysed in two different cultivation systems (i.e. based on air-bubbling and on shaking) and for different initial biomass concentrations. Floc formation and biomass settling were monitored during batch cultivation tests according to an innovative protocol. Results showed that the two cultivation systems enhanced two different flocculation behaviours: air bubbling led to the formation of small and dense flocs, while the shaking table resulted in larger (14 mm2 vs 4 mm2) but mechanically weaker flocs. Floc analysis evidenced that the different mixing systems also affected the speciation of biomass. A mathematical model was developed to simulate and predict the settling performance during the bioflocculation process of filamentous cyanobacteria. Natural settling was examined at different phases of biomass growth. Optimal conditions were obtained at the end of the exponential growth phase, when 70% of the total cultivated biomass could be recovered