Fig. 2: Extracellular electron transfers of C. malenominatum and EET promotes methylotrophic methanogenesis by M. luminyensis.
A C. malenominatum was 10% inoculated in pre-reduced MM medum containing the indicated concentrations of ferric citrate and incubated at 37 °C, and ferrous ion accumulation was determiend. B C. malenominatum (C.m) was 10% inoculated in the MM medium without sulfide and resazurin inside a cathode H-cell reactor with a potential of +0.4 V versus Ag/AgCl. An electrochemical culture without inoculation (-) served as abiotic control. The electrochemical cultures were mixed by a magnetic stir bar, and current production was monitored during incubation at 37 °C. Experiments were performed on three batches of culture, and one representative dataset is shown. C M. luminyensis was 10% (0.1 mg total cell protein) inoculated in a H-cell containing pre-reduced MM medium with 400 μmol methanol, and purged with 100% N2 gas. An uninoculated H-cell served as an abiotic control. The cathode potential was set at −0.4 V in the first 8-day incubation at 37 °C and then reduced to −0.6 V and −0.8 V as indicated. Productions of CH4 and H2 were monitored. D Current consumption and methane production were measured in the same electrochemical reactor as in (C) at −0.4 V potential of the cathode. A final concentration of 10 mM 2-Bromoethanesulfonate (BES) was added after 48 h as indicated by arrow. Two independent experiments were performed, and one representative is shown here.
