The different behaviour of Thermotoga neapolitana in the anodic and cathodic compartment of a bioelectrochemical system

Pierangela Cristiani,Giuliana D’Ippolito,Silvia Franz,Angelo Fontana,Massimiliano Bestetti,Nunzia Esercizio,Mariamichela Lanzilli,Laura Malavola

doi:10.1051/e3sconf/202233408008

Abstract

Thermotoga neapolitana is a hyperthermophilic bacterium that can metabolize glucose and several organic wastes in hydrogen and lactate at a temperature of 80°C. Their high performance in producing hydrogen at so high a temperature as 80°C suggests a potential energy application of them where hydrogen is an important element of the process. In this view, experimentation of a T.neapolitana strain is carried out in double-chamber electrochemical systems. The aim is to explore the interaction of these bacteria with the anode and the cathode, stressing their capability to survive in presence of a polarized electrode which can drastically change the pH of the media. A culture enriched of 5 g/L of glucose, under CO2 pressure (80 °C) was used to fill both the anodic and cathodic compartments of the electrochemical system, applying a voltage of 1.5 V between the anode and the cathode. The test lasted ten days. Results clearly indicate that bacteria colonize both electrodes, but the glucose metabolism is completely inhibited in the anodic compartments. On the contrary, metabolism is stimulated in the cathodic compartment. Bacteria are alive on the electrodes in the pH interval of 3 - 9.

Highlights

The use of single strains in hyperthermophilic conditions is a possible innovative way to make electrochemical systems simpler to manage and efficient
Boron Doped Diamond (BDD), which is known to control the formation of reactive oxidant substances (ROS) at potential >1 V [4] is used in comparison with carbon cloth anodes in the second test
The data produced in this work confirmed that it is possible to drive the metabolism of hyperthermophilic bacteria T. neapolitana in polarized bioelectrochemical reactors

Summary

Introduction

The use of single strains in hyperthermophilic conditions is a possible innovative way to make electrochemical systems simpler to manage and efficient. Previous works, [1, 2] found a great affinity of T. neapolitana to form biofilm on different materials In principle, they can be exploited to catalyze the hydrogen evolution reaction in a microbial electrolytic cell, with the aim to improve the overall yield of the system, as recently attempted [3]. The previous tests were performed in single-chamber electrochemical systems, using an alternated polarization between electrodes [2] Those conditions could not allow differentiating the behaviour of the bacterial colony on anode or cathode. Aiming at exploring separately the interaction of the hyperthermophilic bacteria with the anode and the cathode electrodes, new tests of a T. neapolitana strain in double-chamber electrochemical systems have been carried out.

Methods

Results

Conclusion