Harnessing hyperthermophilic metabolism to boost bioelectrochemical systems: Key thermodynamic challenges

This work analyzes and emphasizes potential advantages of harnessing hyperthermophilic metabolisms in electrochemical systems. The metabolic strategies that allow microorganisms to survive at extreme temperatures as high as 115 °C are critically discussed. The interconversion between standard states and their biological counterparts is highlighted, detailing variations in free energy and activity coefficients, in the interval of 25–115 °C, for some chemical species participating in crucial energetic reactions of microbial metabolisms. Specific reactions involving the oxidation of carbon, nitrogen, and sulfur are relevant semi-reactions possibly occurring at the anode or at the cathode in bioelectrochemical systems. Special attention is given to methane production by hyperthermophilic archaea and sulfur cycle processes mediated by bacteria causing microbial corrosion. These topics are identified as areas deserving further research efforts and hold potential for technological innovation.