The oxidation of organic matter coupled with the reduction of metal ores, like Fe (III) or Mn (IV), is the most important biogeochemical process in soils, aquatic sediments and groundwater. These processes are based on metal-reducing microorganisms that perform anaerobic respiration and utilize metals as terminal electron acceptor [1]. This is achieved by microbial extracellular electron transfer, which these so-called electroactive microorganisms (EAM) are capable of. EAM include both obligate, such as Geobacteraceae, as well as facultative anaerobes, such as Shewanella spp. In bioelectrochemical systems, EAM transfer electrons to a solid electrode instead of metals [2]. A distinct ecological niche cannot be defined and due to the enormous microbial diversity in different habitats, systematic screening for EAM is one of the greatest challenges that is currently methodically hampered due to unavailable electrochemical screening tools [3].
Our aim is to establish a high throughput screening platform that allows independent electrochemical systems to be investigated in parallel and real-time. The requirements are to perform basic electrochemical measurement methods such as chronoamperometry and cyclic voltammetry in a 3-electrode-setup to screen for EAM in long-term operation under anaerobic conditions.
To tackle this challenge, we developed a 96 electrochemical deepwell plate and a 96-channel multipotentiostat to investigate 96 independent controllable samples. Electrochemical cultivation of the model organisms Geobacter sulfurreducens and Shewanella oneidensis achieved maximum current densities and coulombic efficiencies that were well in-line with literature [4].
This easy-to-use system will allow to gain deeper insights into the physiology and diversity of EAM and allow their targeted development for use in a biobased and electrified economy.
Funding: This research is funded by the German Federal Ministry of Education and Research (BMBF) under the grant number 031B1378C.
References:
[1] Lovley DR, Microbiol Rev 1991, 55(2), DOI: 10.1128/mr.55.2.259-287.1991
[2] Logan BE, et al. Nat Rev Microbiol 2019, 17(5), DOI: 10.1038/s41579-019-0173-x
[3] Koch C, et al. ChemElectroChem 2016, 3 (9), DOI: 10.1002/celc.201600079
[4] Kuchenbuch A & Frank R, et al. Front Bioeng Biotechnol 2022, 15 (9), DOI: 10.3389/fbioe.2021.821734