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Item type:Publication, Access status: with files , Flow-driven structural and transcriptomic responses in syntrophic electroactive biofilms(Elsevier, 2026-07-07); ; ; ; Bioelectrochemical systems (BES) are versatile platforms for energy and resource recovery, where electroactive biofilms serve as the key biocatalyst. While performance depends on flow dynamics, the interplay between hydrodynamic conditions, biofilm architecture, and gene-regulation in syntrophic communities remains poorly understood. We investigated defined surface flow velocities (0.2 and 0.8 mm/s) on the structure and electroactivity of Shewanella oneidensis–Geobacter sulfurreducens coculture biofilms. Higher flow produced more compact biofilms with lower biovolume and porosity, yielding higher current densities. Flow transitions induced persistent structural and electrochemical shifts, indicating an adaptive, gene-regulated response to shear. Since G. sulfurreducens monoculture biofilms were flow-insensitive, regulation appears to originate from S. oneidensis. Transcriptomics showed strong shear response, including 10.7-fold upregulation of bpfD. Its deletion reduced current density and increased porosity despite comparable biovolume. Three-dimensional fluorescence in situ hybridization imaging revealed a porous, loosely organized structure within the mutant biofilm. This was consistent with the structural and electrochemical differences observed. These findings reveal that community-level electrochemical performance can be governed by a minor transcriptional contributor rather than by the dominant current-producing species.Publicationtype: Journal Article15 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Assessing the impact of transposon activity and megaplasmid characteristics on the genetic stability of the model organism shewanella oneidensis(2026); The facultative anaerobe Shewanella oneidensis is a model organism widely studied for its extracellular electron transfer capabilities, making it a promising candidate for bioelectrochemical systems (BES). However, its presumed genetic instability presents a key challenge, particularly for long-term industrial applications. This study investigates two major factors influencing genetic robustness in S. oneidensis: transposon activity and the presence of the megaplasmid (MP). Transposable elements (TEs) play a crucial role in genome plasticity. Their high activity can lead to disruptive mutations, compromising strain stability. To assess transposase mobility under TE-activating conditions, transcriptomic analysis and stress-induced transposition experiments were combined with whole-genome sequencing. The results indicate that certain insertion sequences (IS), particularly ISSOD1, ISSOD2 and ISSOD9, exhibit high transposition rates, contributing to genetic instability. To mitigate these effects, CRISPR-Cas-deaminase-based genome editing was employed to introduce premature stop codons into active transposase genes. This deactivation successfully reduced transposase-related mutations emanating from the ISSOD2 family, demonstrating a viable strategy for stabilizing the S. oneidensis genome. ISSOD9 activity appeared to be strongly linked to the presence of plasmids in transformed strains, suggesting its transposition mechanism is associated with horizontal gene transfer. This finding has significant implications for studies utilizing external plasmids, as it underscores the potential for unintended genomic alterations. In parallel, the role of the megaplasmid in genetic stability was examined, which harbors numerous TEs and contains mutation-prone regions, increasing TE motility potential. Using an adaptive evolutionary approach, it was attempted to delete the MP while circumventing post-segregational killing caused by toxin-antitoxin pairs that contribute to stabilized vertical plasmid transfer. Although complete megaplasmid loss was not achieved, approximately 35 % of its sequence was deleted, including nine TEs and an identified hotspot for integration. Notably, the unexpected loss of the region containing the origin of replication suggests a metastable state for the MP. By integrating genome-wide analyses with targeted genetic modifications, this study provides valuable insights into the mechanisms governing genetic stability in S. oneidensis. These findings contribute to optimizing S. oneidensis as a robust production strain for BES applications, with broader implications for microbial engineering and industrial biotechnology.Publicationtype: Doctoral Thesis44 31 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Influence of different transposon families on genomic stability of Shewanella Oneidensis MR1Shewanella oneidensis, recognised as an important model organism for exoelectrogenic electron transport, has been extensively studied for its potential applications in bioelectrochemical systems. To date, the activity of transposable elements in this organism has not been conclusively investigated. This study focused on transposases, specifically insertion sequences (IS), which make up approximately 4.7% of the organism's genome, and evaluated their impact on genome stability under stress conditions. Using whole genome sequencing, two IS families, ISSOD1 and ISSOD2, were identified as the most active, both showing similar transposition patterns across all tested stressors. A CRISPR/dCas9 cytosine deaminase system was used to introduce stop codons in the ISSOD2 transposase genes, resulting in a significant reduction of transposition events under stress conditions. Analysis of transposition patterns revealed a high frequency of insertions occurring on the megaplasmid, which predominantly carries non-essential genes. Experiments performed here to delete the megaplasmid resulted in the elimination of approximately 35% of its sequence, including an unexpected complete loss of the ori/repA region. Therefore, it was hypothesised that the megaplasmid either exists in a metastable state, possibly representing a cointegrated intermediate within the ISSOD9 (Tn3 member) transposition mechanism, or consists of two replicons that have been combined in previous assemblies due to long overlapping homologies resulting from the presence of ISSOD9. These findings highlight the dynamics of transposable elements in S. oneidensis and suggest strategies to improve strain stability by inactivating these elements and at least reducing megaplasmid sequences. Such approaches could improve the suitability of the organism for industrial applications.Publicationtype: Journal Article14 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Data-driven assessment of the der flexibility impact on the LV grid managementLow voltage (LV) grids face a challenge of effectively managing the growing presence of new loads like electric vehicles and heat pumps, along with the equally growing installation of rooftop photovoltaic panels. This paper describes practical applications of sensitivity factors, extracted from smart meter data (i.e., without resorting to grid models), to i) link voltage problems to different costumers/devices and their location in the grid, ii) manage the flexibility provided by distributed energy resources (DERs) to regulate voltage, and iii) assess favorable locations for DER capacity extensions, all with the aim of supporting the decision-making process of distribution system operators (DSOs) and the design of incentives for customers to invest in DERs. The methods are tested by running simulations based on historical meter data on six grid models provided by the EU-Joint Research Center. The results prove that it is feasible to implement advanced LV grid analysis and management tools despite the typical limitations in its electrical and topological characterisation, while avoiding the use of computationally heavy tools such as optimal power flows.Publicationtype: Conference Paper6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Hierarchical Online-Optimization for the Control of Flexible Loads and Generators in Distribution Grids(2021-11); ; This paper proposes a hierarchical online algorithm to solve a multi-level Optimal Power Flow problem in distribution grids with a high penetration of distributed energy resources. Based on an overall utility function, the developed method aims to optimize the usage of controllable loads and generators while maintaining compliance with the defined engineering constraints. The hierarchical control architecture is composed of a superordinate controller and several regional controllers that operate on lower levels. Using an online projected gradient method, the controllers compute incremental changes for the active power setpoints and use mutual communication to capture real-time measurements of power injections, nodal voltages and line currents. The hereby created feedback loop allows to accurately monitor the grid state and detect potential limit violations. The developed algorithm is tested using time series simulations in a MATLAB/SIMULINK environment. It is shown that the hierarchical controller is suitable for controlling exemplary critical power flow scenarios, while enabling higher computational efficiency since the computations are distributed among multiple units.Publicationtype: Conference Paper33