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Bioelectricity generation, by Shewanella oneidensis ( S. oneidensis ) MR-1, has become particularly alluring, thanks to its extraordinary prospects for energy production, pollution treatment, and biosynthesis. Attempts to improve its technological output by modification of S. oneidensis MR-1 remains complicated, expensive and inefficient. Herein, we report on the augmentation of S. oneidensis MR-1 with carbon dots (CDs). The CDs-fed cells show accelerated extracellular electron transfer and metabolic rate, with increased intracellular charge, higher adenosine triphosphate level, quicker substrate consumption and more abundant extracellular secretion. Meanwhile, the CDs promote cellular adhesion, electronegativity, and biofilm formation. In bioelectrical systems the CDs-fed cells increase the maximum current value, 7.34 fold, and power output, 6.46 fold. The enhancement efficacy is found to be strongly dependent on the surface charge of the CDs. This work demonstrates a simple, cost-effective and efficient route to improve bioelectricity generation of S. oneidensis MR-1, holding promise in all relevant technologies. Bacterial fuel cells have generated attention with the prospect of green energy production; current research is focused on optimising the system to improve efficiency. Here, the authors report on the feeding of carbon dots to S. oneidensis MR-1 to enhance metabolic activity and bioelectric generation.

Bacterial nanowires offer an extracellular electron transport (EET) pathway for linking the respiratory chain of bacteria to external surfaces, including oxidized metals in the environment and engineered electrodes in renewable energy devices. Despite the global, environmental, and technological consequences of this biotic–abiotic interaction, the composition, physiological relevance, and electron transport mechanisms of bacterial nanowires remain unclear. We report, to our knowledge, the first in vivo observations of the formation and respiratory impact of nanowires in the model metal-reducing microbe Shewanella oneidensis MR-1. Live fluorescence measurements, immunolabeling, and quantitative gene expression analysis point to S. oneidensis MR-1 nanowires as extensions of the outer membrane and periplasm that include the multiheme cytochromes responsible for EET, rather than pilin-based structures as previously thought. These membrane extensions are associated with outer membrane vesicles, structures ubiquitous in Gram-negative bacteria, and are consistent with bacterial nanowires that mediate long-range EET by the previously proposed multistep redox hopping mechanism. Redox-functionalized membrane and vesicular extensions may represent a general microbial strategy for electron transport and energy distribution.

The demand for reduced chemical preservative usage is currently growing, and natural preservatives are being developed to protect seafood. With its excellent antibacterial properties, linalool has been utilized widely in industries. However, its antibacterial mechanisms remain poorly studied. Here, untargeted metabolomics was applied to explore the mechanism of Shewanella putrefaciens cells treated with linalool. Results showed that linalool exhibited remarkable antibacterial activity against S. putrefaciens, with 1.5 µL/mL minimum inhibitory concentration (MIC). The growth of S. putrefaciens was suppressed completely at 1/2 MIC and 1 MIC levels. Linalool treatment reduced the membrane potential (MP); caused the leakage of alkaline phosphatase (AKP); and released the DNA, RNA, and proteins of S. putrefaciens, thus destroying the cell structure and expelling the cytoplasmic content. A total of 170 differential metabolites (DMs) were screened using metabolomics analysis, among which 81 species were upregulated and 89 species were downregulated after linalool treatment. These DMs are closely related to the tricarboxylic acid (TCA) cycle, glycolysis, amino acid metabolism, pantothenate and CoA biosynthesis, aminoacyl-tRNA biosynthesis, and glycerophospholipid metabolism. In addition, linalool substantially affected the activity of key enzymes, such as succinate dehydrogenase (SDH), pyruvate kinase (PK), ATPase, and respiratory chain dehydrogenase. The results provided some insights into the antibacterial mechanism of linalool against S. putrefaciens and are important for the development and application of linalool in seafood preservation.

Extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. Here we show that flavin molecules secreted by Shewanella oneidensis MR-1 enhance the ability of its outer-membrane c -type cytochromes (OM c- Cyts) to transport electrons as redox cofactors, but not free-form flavins. Whole-cell differential pulse voltammetry revealed that the redox potential of flavin was reversibly shifted more than 100 mV in a positive direction, in good agreement with increasing microbial current generation. Importantly, this flavin/OM c- Cyts interaction was found to facilitate a one-electron redox reaction via a semiquinone, resulting in a 10 ³- to 10 ⁵-fold faster reaction rate than that of free flavin. These results are not consistent with previously proposed redox-shuttling mechanisms but suggest that the flavin/OM c- Cyts interaction regulates the extent of extracellular electron transport coupled with intracellular metabolic activity.

Shewanella xiamenensis BC01 (SXM) was isolated from sediment collected off Xiamen, China and was identified based on the phylogenetic tree of 16S rRNA sequences and the gyrB gene. This strain showed high activity in the decolorization of textile azo dyes, especially methyl orange, reactive red 198, and recalcitrant dye Congo red, decolorizing at rates of 96.2, 93.0, and 87.5 %, respectively. SXM had the best performance for the specific decolorization rate (SDR) of azo dyes compared to Proteus hauseri ZMd44 and Aeromonas hydrophila NIU01 strains and had an SDR similar to Shewanella oneidensis MR-1 in Congo red decolorization. Luria-Bertani medium was the optimal culture medium for SXM, as it reached a density of 4.69 g-DCW L⁻¹ at 16 h. A mediator (manganese) significantly enhanced the biodegradation and flocculation of Congo red. Further analysis with UV–VIS, Fourier Transform Infrared spectroscopy, and Gas chromatography–mass spectrometry demonstrated that Congo red was cleaved at the azo bond, producing 4,4′-diamino-1,1′-biphenyl and 1,2′-diamino naphthalene 4-sulfonic acid. Finally, SEM results revealed that nanowires exist between the bacteria, indicating that SXM degradation of the azo dyes was coupled with electron transfer through the nanowires. The purpose of this work is to explore the utilization of a novel, dissimilatory manganese-reducing bacterium in the treatment of wastewater containing azo dyes.

species ( spp.) were emerging and rare pathogens. Very few studies had focused on spp. infection due to its low incidence. A retrospective analysis summarizing clinical and laboratory characteristics of spp. infection at a tertiary hospital in Hefei City was conducted to learn more about the rare bacterium. A total of 36 patients with spp. infection from October 2019 to February 2025 were included. The data of all patients were collected by reviewing electronic records. Among 36 isolated strains, 77.8% were and 22.2% were . Abdominal pain was the most common clinical symptom. Intrahepatic stone and cholangitis was the main diagnosed disease. According to the type of main diagnosed disease, they were divided into two groups: hepatobiliary disease group and non-hepatobiliary disease group. The laboratory results were analyzed, and it was revealed that the laboratory characteristics of anemia, neutrophilia, leukocytosis, and so on were common. Serum coagulation tests results showed that it was significantly higher than the normal value, and all other serum biochemical and coagulation tests results were mostly normal. For microorganism culture, co-infection microorganisms were obtained. spp. were usually susceptible to aminoglycoside, quinolone, cephalosporin, carbapenems, and compound antibiotics. All patients were treated with antibiotics, and there were one or more types of antibiotics to use, all of whom had effective treatment outcomes. spp. infections were very limited. The study might improve the attention and awareness of the rare bacterial infection.

Bioelectrochemical systems rely on microorganisms to link complex oxidation/reduction reactions to electrodes. For example, in Shewanella oneidensis strain MR-1, an electron transfer conduit consisting of cytochromes and structural proteins, known as the Mtr respiratory pathway, catalyzes electron flow from cytoplasmic oxidative reactions to electrodes. Reversing this electron flow to drive microbial reductive metabolism offers a possible route for electrosynthesis of high value fuels and chemicals. We examined electron flow from electrodes into Shewanella to determine the feasibility of this process, the molecular components of reductive electron flow, and what driving forces were required. Addition of fumarate to a film of S. oneidensis adhering to a graphite electrode poised at -0.36 V versus standard hydrogen electrode (SHE) immediately led to electron uptake, while a mutant lacking the periplasmic fumarate reductase FccA was unable to utilize electrodes for fumarate reduction. Deletion of the gene encoding the outer membrane cytochrome-anchoring protein MtrB eliminated 88% of fumarate reduction. A mutant lacking the periplasmic cytochrome MtrA demonstrated more severe defects. Surprisingly, disruption of menC, which prevents menaquinone biosynthesis, eliminated 85% of electron flux. Deletion of the gene encoding the quinone-linked cytochrome CymA had a similar negative effect, which showed that electrons primarily flowed from outer membrane cytochromes into the quinone pool, and back to periplasmic FccA. Soluble redox mediators only partially restored electron transfer in mutants, suggesting that soluble shuttles could not replace periplasmic protein-protein interactions. This work demonstrates that the Mtr pathway can power reductive reactions, shows this conduit is functionally reversible, and provides new evidence for distinct CymA:MtrA and CymA:FccA respiratory units.

Biofilm formation is a survival strategy for bacteria, contributing to their persistence in natural and industrial environments. In this study, we investigated the ability of extracellular products (ECPs) produced by the probiotic strain Shewanella sp . Pdp11 under different culture conditions to inhibit biofilm formation in pathogenic and environmental Shewanella strains. ECPs from specific culture conditions altered biofilm formation in several Shewanella strains, with Shewanella hafniensis P14 displaying the highest sensitivity. Metabolomic analysis of the ECPs identified glycogen as a key metabolite associated with biofilm inhibition. Further genomic analysis of S . hafniensis P14 revealed an interruption in its glycogen synthesis pathway, suggesting a dependency on external glycogen-related metabolites for biofilm development. These findings demonstrate that Shewanella sp. Pdp11 ECPs can modify biofilm formation across multiple Shewanella strains, particularly in S . hafniensis P14 through glycogen-associated mechanisms.

The pathogenic profiles of seven Shewanella spp. positive cases identified during diarrhea surveillance in Beijing, China, in 2023 were characterised. Sentinel hospitals collected patient information and stool samples, while regional centres for disease control (CDC) performed cultures and real time PCR. Whole-genome sequencing (WGS), average nucleotide identity (ANI) analysis, phylogenetic analysis, virulence gene and resistance gene analysis of the Shewanella spp. isolates were conducted, as well as phenotypic resistance analysis. The detection rate in the stool samples collected from 354 diarrhea patients was 1.98% (7/354). The time of disease onset of six out of the seven patients ranged from July 17–22, 2023. The incubation period ranged from 8 to 12 h with 3–50 episodes/day. Three subjects reported having consumed potentially contaminated seafood. The seven isolated strains of Shewanella spp. (named as S1-S7) were closely related to S. algae , belonged to the algae clade, and were all novel ST (sequence typing) strains. A total of 125,738 SNPs (single nucleotide polymorphism) were identified in the core genomes of the seven Shewanella strains. Twenty-six virulence-related genes in five categories were identified, with chemotaxis and flagella-related genes being the most abundant (26.92%, 7/26), followed by secretion system- and serum resistance-related genes at 23.08% (6/26) and 15.38% (4/26), respectively. Shewanella spp. were detected in patients with diarrhea at a certain level. Seafood should be the key food category for monitoring and seafood markets should become a key monitoring site for Shewanella spp. The novel STs of the algae clade isolated from diarrhea patients in this study may potentially help in tracking circulating strains. Further in-depth investigations are required to precisely elucidate the correlation between Shewanella infections and human diarrhea and the pathogenic characteristics of this infection.

Electrochemically active bacteria (EAB) receive considerable attention for their utility in bioelectrochemical processes. Although electrode potentials are known to affect the metabolic activity of EAB, it is unclear whether EAB are able to sense and respond to electrode potentials. Here, we show that, in the presence of a high-potential electrode, a model EAB Shewanella oneidensis MR-1 can utilize NADH-dependent catabolic pathways and a background formate-dependent pathway to achieve high growth yield. We also show that an Arc regulatory system is involved in sensing electrode potentials and regulating the expression of catabolic genes, including those for NADH dehydrogenase. We suggest that these findings may facilitate the use of EAB in biotechnological processes and offer the molecular bases for their ecological strategies in natural habitats. Whether electrochemically active bacteria (EAB) can gain energy according to electrode potentials is still unclear. Here, the authors show through transcriptome and deletion mutant analyses that EAB can sense electrode potentials by the Arc system and activate NADH-dependent catabolic pathway to generate ATP.