Effect of the anode potential on the physiology and proteome of Shewanella oneidensis MR-1

Abstract

Shewanella species respire using iron and manganese oxides as well as electrodes as solid terminal electron acceptors. Shewanella oneidenis MR-1 exploits mediated as well as direct extracellular electron transfer (EET) modes to transfer electrons at different formal potentials. These different EET modes at different potentials may utilise alternate electron transfer pathways. Therefore, we investigated how different anode potentials, providing different maximum microbial energy gains impacted S. oneidensis microbial physiology. Using quantitative proteomics, comparative analysis of the cellular variations to different anode potentials was performed. A label-free proteomic mass spectrometric analysis method, SWATH-MS, was used to gather quantitative information to determine physiological changes of Shewanella oneidensis MR-1 grown at different anodic potentials. S. oneidensis was cultured and grown in electrochemical cells at the set anode potentials of +0.71V, +0.21V & -0.19V versus SHE reference electrode, while the current production was monitored. At maximum current, electrodes were removed and whole-cell proteins extracted. Subsequent SWATH-MS analysis revealed information on 740 identified proteins across the three electrode potentials. For the first time, we show the abundance of S. oneidensis electron transfer proteins differs with electrode potential.

Enhanced Current Production by Exogenous Electron Mediators via Synergy of Promoting Biofilm Formation and the Electron Shuttling Process

“…oneidensis MR-1 cells to the electrodes. All the pure EMs showed clear redox peaks (red line), while the EMs with biofilm revealed a sigmoidal anodic current profile characteristic of catalytic activity (black line). This positive current was observed above a potential of mid-potential of EMs, reflecting the flow of electrons from bacteria to electrodes.…”

“…The data (Figure 2a) showed that, while the peak oxidative current of biofilm without EMs was very low (black line, 0.05 mA), much higher currents (1−3 mA) were observed in all the BESs with EMs (Figure 2b−f), indicating that the redox cycling of EMs should have a comparatively high contribution to the overall electron flux from S. oneidensis MR-1 cells to the electrodes. All the pure EMs showed clear redox peaks (red line), while the EMs with biofilm revealed a sigmoidal anodic current profile characteristic 58 of catalytic activity (black line). This positive current was observed above a potential of mid-potential of EMs, reflecting the flow of electrons from bacteria to electrodes.…”

Electrosynthesis of acetate from inorganic carbon (HCO3−) with simultaneous hydrogen production and Cd(II) removal in multifunctional microbial electrosynthesis systems (MES)

“…With regard to the cathodic electrons used for acetate production, hydrogen evolution and Cd(II) removal, it is difficult to exactly quantify the amounts of electrons used by each product. Although, electron acceptors (HCO3 -, H + , or Cd(II)) are beneficial for the electron transfer process from the cathode [46], it has yet to be demonstrated that electron transfer to these species are also associated to cell respiration. In fact there are a variety of other possible mechanisms by which bacterial cells might catalyze the reduction of Cd(II), and the production of acetate and hydrogen [47].…”

Electric current generation through the Wickerhamomyces anomalus yeast

“…Se realizó por triplicado [17]. como sustrato [19], así como también al enriquecimiento con microbio electroactívo en el ánodo y a las transferencias de electrones o a la autorregulación de las vías extracelulares de 60 transferencia de electrones [20][21][22]. El descenso de los valores de voltaje y corriente en los últimos días se debería a la difusión de oxígeno del cátodo al ánodo debido a la falta de una membrana entre ellos [23].…”