Evaluating the Feasibility of Microbial Electrosynthesis Based on Gluconobacter oxydans

Abstract

Primary microbial electrochemical technologies are utilizing the interfacing of microbial redox reactions and electrodes. Based on its exploitation as recognition element for bioelectrochemical glucose sensors and inspired by its biotechnological potential Gluconobacter oxydans was studied on its suitability for microbial electrosynthesis. It is demonstrated that in bioelectroreactors the conversion of glucose by G. oxydans based on mediated extracellular electron transfer is not related to electric current flow. Oxidation current can only be recorded after preceding aeration phase, but the response does strongly depend on the microbial activity status, pO2 and gas supply as well as the pH regime. It is proven that the electric current is derived from the microbial cells, but the mechanism still needs to be elucidated. The suitability of G. oxydans for microbial electrosynthesis but also for bioelectrochemical sensors is critically assessed.

Integrating Electrochemistry Into Bioreactors: Effect of the Upgrade Kit on Mass Transfer, Mixing Time and Sterilizability

“…In general, the polymer-based ion exchange membrane (fumasep FKE, FuMA-Tech GmbH, Bietigheim-Bissingen, Germany) was glued using a two-component epoxy adhesive on the inner side of the inlay, as described above and shown in Figure 2 (Gimkiewicz et al, 2016). Three different methodologies were used to study the sterilization of the inlay with the glued membrane and to test the stability of membrane material and gluing.…”

“…Thus, the sterilization of the upgrade kit as well as of the other parts not present in the conventional bioreactor need to be demonstrated. Preliminary considerations about sterilizable materials and sterilization procedures can already be found (Gimkiewicz et al, 2016;Enzmann et al, 2019), and recently sterilizability of electrodes for a secondary MES was FIGURE 6 | Measurement of k L a values for setups 1 (black), 3 (green), and 4 (red) at various gassing rates (triangles 0.5 sLpm; circles 1 sLpm; and squares 2 sLpm). Error bars represent the confidence interval at 95% confidence calculated from at least 5 independent measurements (n ≥ 5).…”

“…Using the upgrade kit, two-chamber 1 L electrobioreactors based on batch stirred tank reactors (BSTR) were achieved (see Figure 1 and Figure SI 1). We demonstrated that the material and design of electrodes and other components of the 1 L electrobioreactors can be achieved allowing research on several pure cultures of electroactive microorganisms, e.g., Gluconobacter oxidans (Gimkiewicz et al, 2016), Clostridium kluyveri (Koch et al, 2017), Shewanella oneidensis (Rosa et al, 2017), and genetically modified E. coli (Mayr et al, 2019). However, to what extent the insertion of electrodes, an inlay creating two chambers, and the use of an adapted stirrer as well as removal of chicanes resulted in change of fluid dynamics remained unclear, and is addressed within this study.…”

Engineering electrochemical CO2 reduction to formate under bioprocess‐compatible conditions to bioreactor scale

“…These bioreactors (sometimes being also denominated as fermentors) are resembling the smallest scale of interest for bioprocess engineering. Electrobioreactors have been used previously for cultivating and investigating the electroactivity of microbial pure cultures for a period of several days . However, so far no benchmarking of the electrobioreactors from an engineering viewpoint was performed and no electrochemical synthesis of formate from CO 2 has been studied therein.…”

Predicting and experimental evaluating bio-electrochemical synthesis — A case study with Clostridium kluyveri

“…The here studied compounds are 2hydroxy-1,4-naphthoquinone (HNQ), methylene blue (MB), neutral red (NR), methyl viologen (MV), cobalt hexaamine [Co(trans-diammac)] 3+ (CoHex) and potassium ferrocyanide (FECY). All of thesemolecules have already either been applied for bio-electrochemical studies with other microorganisms (HNQ[28], MB[39]) as well as for Clostridia specifically (NR, MV[9], CoHex[25]) or served in biosensors and as electrochemical model compounds in general (FECY[40]).…”