Overexpression of c‐type cytochrome, CymA in Shewanella oneidensis MR‐1 for enhanced bioelectricity generation and cell growth in a microbial fuel cell

Abstract

BACKGROUND: The c-type cytochrome of the CymA of Shewanella oneidensis MR-1 is essential for the anaerobic respiration of Shewanella sp. and transfers electrons from the inner membrane to various terminal electron acceptors, such as soluble redox shuttles and insoluble metal oxides. CymA is believed to be a passage to the outer membrane for dissipating the respiratory electron to the carbon electrode in a microbial fuel cell (MFC) with simultaneous electricity generation. While the deletion and heterologous expression of cymA in Escherichia coli have been studied, there are no reports of the overexpression and its effects on the corresponding bioelectrochemical performance in a MFC. RESULTS:The cymA gene was overexpressed in Shewanella oneidensis MR-1, and its upregulation was examined under aerobic, anaerobic, and MFC operating conditions by a reverse transcription-polymerase chain reaction (RT-PCR). Overexpression of the CymA protein was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The MFCs inoculated with the engineered strains of MR-1 achieved a higher maximum power of 0.13 mW and specific growth rate of 0.087 h −1 than those of the wild type MR-1 (0.11 mW and 0.043 h −1 , respectively). The higher electrochemical activity of the mutant strains demonstrated by cyclic voltammetry and linear sweep voltammetry, indicates that more respiratory electrons can be transferred to the electrodes through overexpression of the cymA gene of MR-1 in a MFC. CONCLUSION: Overexpression of CymA improves the bioelectrochemical performance of MFCs. This suggests that metabolic engineering of a membrane-associated redox protein, such as CymA, can further improve electricity generation of MFCs and produce an electrochemically enhanced bioprocess. Industry phosphate buffer (pH 7.0) and resuspended with the same buffer.The re-suspended cells were disrupted using a bead beater (Fastprep FP120, Fisher Scientific, Hampton, NH, USA) at a speed of 6.0 for 20 s per cycle for a total of 5 cycles. The disrupted cells

The interaction between microbes and electrodes decorated with bio‐reduced graphene oxide— from an electrochemical point of view

“…3(b)). The occurrences of those two CV peaks were attributed to the redox sensitive functional group of the c‐type cytochrome in cells 41‐43 …”

“…The occurrences of those two CV peaks were attributed to the redox sensitive functional group of the c-type cytochrome in cells. [41][42][43] The EET quantity (ETQ) between different electrodes and microbes could be obtained according to the baseline corrected CV curves. 32 The ETQ between the GO-br-CF electrode and microbes increased significantly along with different incubation times (Fig.…”

Potential of Zymomonas mobilis as an electricity producer in ethanol production

“…Frequently, the EET pathway is a bottleneck for further improving the voltage output of exoelectrogens [31]. It consists of an indirect electron shuttle-meditated pathway [32] and the direct pathways, including appendages [33], nanowires [34] and c-type cytochrome [35]. Hence, adding electron shuttles and c-type cytochrome was implemented to enhance the EET pathway.…”

Potential of Zymomonas mobilis as an electricity producer in ethanol production

“…Frequently, the EET pathway is a bottleneck for further improving the voltage output of exoelectrogens [27]. It consists of an indirect electron shuttle-meditated pathway [28] and the direct pathways, including appendages [29], nanowires [30] and c-type cytochrome [31]. Hence, adding electron shuttles and c-type cytochrome was implemented to enhance the EET pathway.…”