Dark-fermentative biohydrogen pathways and microbial networks in continuous stirred tank reactors: Novel insights on their control

Rodolfo Palomo-Briones (1) , Elías Razo-Flores (1) , Nicolas Bernet (2) , Eric Trably (2)

1 División de Ciencias Ambientales
2 LBE - Laboratoire de Biotechnologie de l'Environnement [Narbonne]

In the present work, the influence of hydraulic retention time (HRT) on dark fermentation metabolism was evaluated through the operation and analysis of a series of four continuous stirred tank reactors (CSTR) at four HRT ranging from 6 h to 24 h. A maximum volumetric hydrogen production rate (VHPR) of 2000 ± 149 mL/L-d corresponding to an H2 yield of 0.86 molH2/mollactose was observed at 6 h HRT. In depth analysis of metabolite profiles and microbial communities showed that low values of HRT favored the emergence of a community dominated by Clostridiaceae-Lachnospiraceae-Enterobacteriaceae, which performed metabolic pathways co-producing hydrogen. In contrast, long HRT led to the establishment of Sporolactobacillaceae-Streptococcaceae microbial community that outcompeted hydrogen producing bacteria and was responsible of lactate production. Results suggested that these two communities mutually excluded themselves and HRT can act as an operational parameter to control the microbial communities and consequently the related metabolic pathways.

Mots clés: biohydrogen; dark fermentation; hydrogen-producing bacteria; metabolic network; lactic acid bacteria; microbial community

Mots clés: biohydrogène; réacteur en continu; fermentation sombre; réseau métabolique; microorganisme producteur d'hydrogène; bactérie lactique; communauté microbienne

Domaines: Sciences du Vivant [q-bio]

Rodolfo Palomo-Briones, Elías Razo-Flores, Nicolas Bernet, Eric Trably. Dark-fermentative biohydrogen pathways and microbial networks in continuous stirred tank reactors: Novel insights on their control. Applied Energy, 2017, 198, pp.77-87. ⟨10.1016/j.apenergy.2017.04.051⟩. ⟨hal-01608465⟩