Promoting Shewanella Bidirectional Extracellular Electron Transfer for Bioelectrocatalysis by Electropolymerized Riboflavin Interface on Carbon Electrode

Abstract

The extracellular electron transfer (EET) that connects the intracellular metabolism of electroactive microorganisms to external electron donors/acceptors, is the foundation to develop diverse microbial electrochemical technologies. For a particular microbial electrochemical device, the surface chemical property of an employed electrode material plays a crucial role in the EET process owing to the direct and intimate biotic-abiotic interaction. The functional modification of an electrode surface with redox mediators has been proposed as an effectual approach to promote EET, but the underlying mechanism remains unclear. In this work, we investigated the enhancement of electrochemically polymerized riboflavin interface on the bidirectional EET of Shewanella putrefaciens CN32 for boosting bioelectrocatalytic ability. An optimal polyriboflavin functionalized carbon cloth electrode achieved about 4.3-fold output power density (∼707 mW/m2) in microbial fuel cells and 3.7-fold cathodic current density (∼0.78 A/m2) for fumarate reduction in three-electrode cells compared to the control, showing great increases in both outward and inward EET rates. Likewise, the improvement was observed for polyriboflavin-functionalized graphene electrodes. Through comparison between wild-type strain and outer-membrane cytochrome (MtrC/UndA) mutant, the significant improvements were suggested to be attributed to the fast interfacial electron exchange between the polyriboflavin interface with flexible electrochemical activity and good biocompatibility and the outer-membrane cytochromes of the Shewanella strain. This work not only provides an effective approach to boost microbial electrocatalysis for energy conversion, but also offers a new demonstration of broadening the applications of riboflavin-functionalized interface since the widespread contribution of riboflavin in various microbial EET pathways together with the facile electropolymerization approach.

Metal Ions Impact on <i>Shewanella Oneidensis</i> MR-1 Adhesion to ITO Electrode and the Enhancement of Current Output

“…Start-up time (dashed line) and maximum loading current density (solid lines) vs. metal ion concentrations of Mg 2+ , Cd 2+ , Pb 2+ , and Ca 2+ for S. oneidensis MR-1. American Journal of Analytical Chemistry The data show decreased start-up time consistent with literature experiments [34] [35][36]. Here an increase in the metal ion concentration decreased the start-up time.…”

“…For example, to reduce the start-up time Zhang et al [35] used a glass fiber separator in MFC, as it has a low oxygen transfer coefficient and a low charge transfer resistances. Zou et al [36] reported a much faster start-up rate for polymerized riboflavin (RF) onto carbon cloth (CC) electrode.…”

Using Cathodic Poised Potential Experiments to Investigate Extracellular Electron Transport in the Crustal Deep Biosphere of North Pond, Mid-Atlantic Ridge

“…This taxon was also observed in a few SB, T0, and Tend samples, indicating that this group is a crustal generalist. Shewanellaceaea are well known for their ability for anodic and cathodic EET across multiple environments (Lovley, 2012;Rowe et al, 2018;Zou et al, 2019). Our results suggest that Shewanellacaea can also perform similar electron transfer reactions in the crustal subsurface.…”

Soluble electron acceptors affect bioluminescence from Shewanella woodyi

“…Mutations in the cytochrome c biosynthesis pathway in Photobacterium leiognathi can decrease the intensity of bioluminescence or is present in the bioluminescence pathway in the yellow‐emitting Vibrio fischeri Y‐1 . S. woodyi can secrete redox mediators such as flavins and quinones that can be reused through multiple redox cycles . Shewanella sp.…”