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Item type:Publication, Access status: with files , Tailored enzyme expression modifies Shewanella oneidensis biofilms and increases current density(Elsevier, 2025-06-09); ; ; ; Biofilm formation is the most effective pathway for electron transfer to anodes in bioelectrochemical systems. However, the mechanisms triggering biofilm formation under anoxic conditions, as well as the architectural and compositional factors that positively influence current generation, are not well understood. Recent findings have shown that riboflavin can function similarly to a quorum sensing molecule in the γ-proteobacterium Shewanella oneidensis. Enhanced biofilm formation induced by riboflavin correlates with increased current densities. Only a limited number of candidate proteins were found to have altered concentrations due to this quorum sensing mechanism. This study demonstrates that the catalytic functions of the UDP-N-acetylglucosamine C4 epimerase WbpP and UDP-N-acetyl-D-glucosamine 6-dehydrogenase WbpA affect biofilm formation and lead to increased current density. Using optical coherence tomography, we found that the expression of each protein individually causes specific, quantifiable changes in biofilm architecture, including biovolume, height, and porosity. However, the current density did not significantly differ when these proteins were expressed alone compared to the control. In contrast, co-expression of WbpP and WbpA resulted in a doubling of current density, closely resembling the increases observed with riboflavin-mediated quorum sensing. We hypothesize that riboflavin-based quorum sensing may lead, through several intermediary steps, to the overproduction of WbpA and WbpP, resulting in better attachment to graphite anodes and thus higher current densities.Publicationtype: Journal Article9 18 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Comparative analysis of the influence of BpfA and BpfG on biofilm development and current density in Shewanella oneidensis under oxic, fumarate- and anode-respiring conditions(Nature Publishing Group, 2024-10-05); ; ; ; Biofilm formation by Shewanella oneidensis has been extensively studied under oxic conditions; however, relatively little is known about biofilm formation under anoxic conditions and how biofilm architecture and composition can positively influence current generation in bioelectrochemical systems. In this study, we utilized a recently developed microfluidic biofilm analysis setup with automated 3D imaging to investigate the effects of extracellular electron acceptors and synthetic modifications to the extracellular polymeric matrix on biofilm formation. Our results with the wild type strain demonstrate robust biofilm formation even under anoxic conditions when fumarate is used as the electron acceptor. However, this pattern shifts when a graphite electrode is employed as the electron acceptor, resulting in biofilm formation falling below the detection limit of the optical coherence tomography imaging system. To manipulate biofilm formation, we aimed to express BpfG with a single amino acid substitution in the catalytic center (C116S) and to overexpress bpfA. Our analyses indicate that, under oxic conditions, overarching mechanisms predominantly influence biofilm development, rather than the specific mutations we investigated. Under anoxic conditions, the bpfG mutation led to a quantitative increase in biofilm formation, but both strains exhibited significant qualitative changes in biofilm architecture compared to the controls. When an anode was used as the sole electron acceptor, both the bpfA and bpfG mutations positively impacted mean current density, yielding a 1.8-fold increase for each mutation.Publicationtype: Journal Article11 9