Electrostimulation of hyperthermophile Thermotoga neapolitana cultures.

Hyperthermophile bioelectrochemical systems are seldom investigated although their superior control of microbial consortium and thermodynamic advantages. Hyperthermophilic Thermotogales, for instance, are able to produce hydrogen and lactic acid from wastes better than mesophilic bacteria. Here, the electrostimulation of Thermotoga neapolitana in single-chamber electrochemical bioreactors is studied. The glucose fermentation under CO pressure, as model metabolism, was tested at 80 °C. Results show that a dynamic polarization (±0.8 to ±1.2 V) drives glucose fermentation and biofilm stasis on electrodes. Under this condition, production of lactic acid (33 vs 12 mM) and yields of acetate and hydrogen (with lactic/acetic acid ratio of 1.18) were higher than those achieved with static polarization or open-circuit. Dynamic polarization is possibly exploitable to stimulate T. neapolitana in a hyperthermophile electrochemical system for various applications including control of power-to-gas processes or production of value-added products (hydrogen and lactic acid) from sugary wastes.