Biohydrogen Fermentation and Biomolecules

In this context fermentation processes in mixed cultures can provide an added value to the treatment process by methanization, in the form of biohydrogen and / or biomolecules of industrial interest.

The research carried out on this topic concerns biological processes involving a complex association of microbial communities making it possible to convert organic biomass into biohydrogen and fermentative molecules. The potential of mixed microbial cultures is particularly interesting with regard to their metabolic flexibility allowing adaptation to many complex organic resources (effluents, biomass).

The aim of the research is to optimize the conversion of biomass into bioH2 and biomolecules by fermentation in mixed cultures, with a focus on:

• The determination of the criteria (composition, structure) allowing to select the best types of inputs according to the considered molecules (H2, lactate, ethanol, acetate, butyrate, caproate, ...). For this, models linking the main characteristics of the inputs and the associated fermentative molecules are developed. Targeted pretreatments are then made to guide the fermentation reactions as well as possible.
• Optimization of the operating conditions in bioprocesses according to the substrates considered (FFOM, straw-type agricultural residues, industrial olive oil, viticultural effluents, or the biodiesel-glycerol industry) and targeted molecules, in particular H2. A particular focus is made on better control of microbial populations during fermentation processes (diversity, biotic control, predictive / explanatory modeling of metabolisms).
• The integration of fermentative processes in an environmental biorefinery scheme. For this, the coupling with the processes of valorization of the produced AGVs is targeted, for the production of either biohythane (H2 + CH4) by methanization of the residues, or of additional H2 in MEC (microbial electrolysis cells), or of biolipids with heterofermental microalgae. 

A particular focus is made on the optimization of the processes by a better control of the processes of interactions between fermentative microorganisms, either by eco-engineering, or by electro-fermentation via the development of complex models of interactions between fermentative microorganisms.

REFERENCES :

• Moscoviz R, de Fouchécour F, Santa-Catalina G, Bernet N & E Trably (2017) Cooperative growth of Geobacter sulfurreducens and Clostridium pasteurianum with subsequent metabolic shift in glycerol fermentation. Scientific Reports, 7: 44334
• Cabrol L, Marone A, Tapia-Venegas E, Steyer JP, Ruiz-Filippi G & E Trably (2017)  Microbial ecology of fermentative hydrogen producing bioprocesses: useful insights for driving the ecosystem function. FEMS Microbiology Reviews, 41: 158-181
• Chatellard L, Trably E & H Carrere (2016) The type of carbohydrates specifically selects microbial community structures and fermentation patterns. Bioresource Technology 221: 541-549
• Moscoviz R, Toledo-Alarcon J, Trably E & N Bernet (2016) Electro-fermentation: how to drive fermentation using electrochemical systems. Trends in Biotechnology 34: 856-865
• Carillo-Reyes J, Trably E, Bernet N, Latrille E & E Razo-Flores (2016) High robustness of a simplified microbial consortium producing hydrogen in long term operation of a biofilm fermentative reactor. International Journal of Hydrogen Energy 41: 2367-2376                
• Benomar S, Ranava D, Cardenas ML, Trably E, Rafrafi Y, Ducret A, Hamelin J, Lojou E, Steyer JP & MT Giudici-Orticoni (2015) Nutritional stress induces exchange of cell material and energetic coupling between bacterial species. Nature Communications 6 : 6283
• Rafrafi Y, Trably E, Hamelin J, Latrille E, Meynial-Salles I, Benomar S, Guidici-Orticoni MT & JP Steyer (2013) Sub-dominant bacteria as keystone species in microbial communities producing bio-hydrogen. International Journal of Hydrogen Energy, 38: 4975-4985