## 2 Materials and Methods
### FNR or FMV Deposition on the MFC\({}_{\text{DSM}}\) Anode  
FNR or FMV was deposited on the MFC\({}_{\text{DSM}}\) anode according to the methodology described by [PERSON] and [PERSON] [17]. The same electrochemical cell employed in Section 2.4 was used. All the solutions were deaerated with N\({}_{2}\) gas.  
To obtain the MFC\({}_{\text{DSM}}\) anode modified with FNR, first a 0.025 M K\({}_{2}\)HPO\({}_{4}\)/KH\({}_{2}\)PO\({}_{4}\) buffer solution (pH = 6) was prepared in 0.10 M KNO\({}_{3}\) containing 1 mM NR. The film was formed by conducting CV from \(-1.0\) to 1.3 V vs. Ag/AgCl\({}_{\text{(sat)}}\) at 50 mV\(\cdot\)s\({}^{-1}\). Different numbers of cycles (10, 15, 20, or 30) were evaluated.  
The MFC\({}_{\text{DSM}}\) anode modified with FMV was prepared under similar conditions. First, a 0.025 M K\({}_{2}\)HPO\({}_{4}\)/KH\({}_{2}\)PO\({}_{4}\) buffer solution (pH = 7) in 0.10 M KNO\({}_{3}\) containing 1 mM MVwas prepared. Then, CV was carried out from \(-1.1\) to 0.2 V vs. Ag/AgCl(sat) at 50 mV\(\cdot\)s\({}^{-1}\). The number of cycles (10, 15, 20, or 30) was evaluated, as well.  
EIS was performed to compare the internal resistance of the unmodified MFCDSM anode with the internal resistance of the MFCDSM anode modified with FNR or FMV. Frequency ranges from 100 kHz to 0.01 Hz and ten frequency points per decade with a root mean square (r.m.s.) sinusoidal perturbation were employed; the amplitude was 10 mV. For the unmodified MFCDSM anode, OCP was used; for the MFCDSM anode modified with FNR or FMV, the potential was \(-0.22\) V or \(-0.16\) V vs. Ag/AgCl(sat), respectively.  
CVs were also run for the MFC anode modified with FNR or FMV in the presence and absence of _C. pasteurianum_ DSM 525. The potential window of \(-0.9\) to \(-0.1\) V vs. Ag/AgCl(sat) was used for _C. pasteurianum_ DSM 525 and FNR, 20 cycles, whereas the potential window of \(-1.1\) to 0.2 V vs. Ag/AgCl(sat) was employed for _C. pasteurianum_ DSM 525 and FMV, 10 cycles.  
Electrochemical Setup and Measurements Obtained by Using C. pasteurianum DSM 525 Alone or in the Presence of NR, MV, FNR, or FMV  
The electrochemical measurements were conducted by using the electrochemical cell setup detailed in Section 2.4. Anperometric _i-t_ tests were performed to evaluate the current density of _C. pasteurianum_ DSM 525 under various conditions: in the absence of a mediator, in the presence of NR or MV, and in the presence of FNR or FMV. These measurements were carried out at a constant potential for 960 s. An anodic overpotential (\(\eta\)) of 250 mV was applied for both mediators. Specifically, tests regarding NR were subjected to \(-0.22\) V vs. Ag/AgCl(sat), while tests involving MV were maintained at a constant potential of \(-0.16\) V vs. Ag/AgCl(sat). The current density was obtained at the end of the amperometric _i-t_ test at 960 s.  
Initially, 20.0, 50.0, 75.0, 100.0, or 150.0 \(\upmu\)M NR or MV was evaluated in LP medium at pH 7.0 (25 \(\pm\) 2 \({}^{\circ}\)C). As for the tests involving FNR or FMV, four CV cycles were employed to obtain the film deposited on the anode. The methodology outlined in Section 2.4 was followed. Subsequently, the anode was transferred to fresh LP medium at pH 7.0 (25 \(\pm\) 2 \({}^{\circ}\)C). Before each test, the solutions were deaerated with N\({}_{2}\).  
For the tests involving _C. pasteurianum_ DSM 525 and NR, MV, FNR, or FMV, DSM 525 was initially activated in RCM medium. After bacterial growth, the cells were transferred to a pre-inoculum containing LP medium, where they remained for 15 h. Then, an aliquot was transferred to another LP medium and incubated for 18 h. The bacterial cell culture was standardized to an O.D. at 600 nm of 0.2. After the O.D. was standardized, the supernatant was removed by centrifugation at 7000 rpm for 5 min and discarded. The resulting cell pellet was added to the assays containing 150.0 \(\upmu\)M NR or MV and to the assays containing FNR or FMV in all cycles.