Search Results (167)

Aqueous organic flow batteries are a promising technology for large-scale energy storage, owing to their safety, low cost, and tunable molecular properties. Battery performance is critically governed by the redox potential, solubility, and stability of organic active species, making molecular design a central research priority. Yet, many current systems still rely on inorganic metal-based materials, which face challenges such as high cost and sluggish kinetics. This review outlines a systematic molecular-engineering framework for designing novel redox species, offering strategies to tailor solubility, redox potential, and molecular size in both organic compounds. Recent advances in mechanistic insight, functionalization, and structure-dependent electrochemical performance are summarized. Computational chemistry and machine learning are highlighted for accelerating high-throughput screening and property prediction, speeding up molecular optimization. Small molecules (1–4 rings), including quinones (C=O), alloxazines, phenazines, and indigo derivatives, which undergo reversible redox reactions involving nitrogen and/or carbonyl groups, have been explored as anolytes and/or catholytes in aqueous redox flow batteries. Key challenges remain, including limited electrochemical stability windows, insufficient solubility, and poor molecular stability, leading to low energy density and cycling degradation. Improving anolyte performance by simultaneously lowering redox potential and enhancing solubility and stability is therefore crucial for advancing both organic and broader redox-active battery systems. Computational and machine learning approaches for identifying and refining electrolyte molecules are also addressed, enabling efficient screening and molecular modification toward high-performance flow batteries. Full article

Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot, one of the most destructive bacterial diseases on crucifer crops, resulting in yield losses of up to 90%. The aim of this study was to identify novel endophytic bacteria from cabbages with potential biocontrol agents against Xcc. A total of sixty-five isolates were evaluated for plant growth-promoting characters and antagonistic activity, from which ten were selected for in planta assays and subsequently validated under field conditions. Pseudomonas synxantha BR25/2 consistently demonstrated the highest efficacy, reducing disease severity by 81.12% in in planta trials and 33.5% in field trials, thereby comparing to copper-based control measures. Additionally, Pseudomonas synxantha BR25/2 significantly enhanced yield parameters, including a 31.8% increase in head weight under field conditions. Whole-genome sequencing identified biosynthetic gene clusters, including siderophores, phenazines, and non-ribosomal peptide synthetases, notably a coronatine-like NRPS and a fengycin-like betalactone, suggesting an extensive antimicrobial potential of metabolites. This represents the first report of P. synxantha exhibiting control over Xcc. For commercial application, large-scale fermentation and encapsulation techniques are recommended to overcome shelf-life challenges, providing a sustainable microbial solution for crucifer production. Full article

Actinomycetes are among the richest sources of bioactive secondary metabolites in biotechnology, owing to their remarkable metabolic diversity. Although the genus Streptomyces has been extensively explored and has yielded many clinically important antibiotics, rare actinomycetes remain comparatively underinvestigated. In this study, Kitasatospora sp. SeTe27, isolated from uncontaminated soil in Sicily (Italy), was investigated for its antibacterial activity and fermentation-driven enhancement of secondary metabolite production. The strain inhibited Staphylococcus aureus ATCC 25923, prompting physiological and genomic analyses. Spore conditioning was evaluated in four media (R5A, GYM, TSB, and YEME) to enhance antibiotic production. Conditioned cultures exhibited markedly increased antibacterial activity in TSB and YEME, moderate production in R5A, and no detectable activity in GYM. Whole-genome sequencing revealed an 8.5 Mb genome (73.5% GC) containing 48 biosynthetic gene clusters (BGCs), including NRPS, PKS, terpene, and hybrid pathways. Several clusters showed high similarity to known antibiotic-associated BGCs, such as clifednamide- and phenazine-related pathways, while numerous orphan clusters indicated significant unexplored biosynthetic potential. These findings identify Kitasatospora sp. SeTe27 as a promising antimicrobial producer and demonstrate that spore conditioning in complex media is an effective strategy to enhance antibiotic production in rare actinomycetes. Full article

Phenazine derivatives are promising metal-free chromophores with strong redox and photophysical properties, yet their use in photocatalytic hydrogenation remains limited. Here, we report a homogeneous phenazine-based system for the visible-light-driven hydrogenation of nitroarenes under mild conditions. Using nitrobenzene as a model substrate and triethanolamine as a sacrificial hydrogen source, the photocatalyst achieved aniline yields of up to 81% after 12 h of irradiation at 390 nm. Systematic variation in reaction parameters revealed that catalyst structure, solvent, and light wavelength strongly influence performance. Kinetic analysis indicated that prolonged irradiation reduces overall yield due to the reconversion of reactive intermediates. The system exhibited higher efficiency toward nitroarenes bearing electron-withdrawing groups, while aliphatic nitro compounds underwent only partial reduction. Mechanistic studies using UV–Vis, fluorescence, and EPR spectroscopy confirmed the formation of persistent radical species and supported a stepwise electron and proton transfer mechanism. This work showcases the potential of phenazine-based photocatalysts as metal-free platforms for nitroarene reduction under visible light. Full article

Nanoparticle-catalysed microwave-aided multicomponent reactions (MCRs) have been demonstrated to be competent and environmentally benign tools for the quick synthesis of a wide spectrum of fused heterocyclic systems. The distinctive physicochemical properties of nanoparticles, including a substantial surface area, readily modifiable surface functionality, and heightened catalytic activities, when coupled with microwave irradiation, have enabled a marked improvement in reaction rates, product yields, and selectivity compared to conventional heating methods. This review highlights recent advancements in microwave-assisted MCRs facilitated by diverse nanomaterials, such as magnetic nanocatalysts, metal and metal oxide nanoparticles, mesoporous silica systems, and nanohybrids. It emphasises catalyst design, catalytic efficacy, scope, recyclability, and alignment with green chemistry principles in both solvent-free and aqueous environments, as well as the utilisation of recyclable catalysts. In summary, microwave-assisted multi-component reactions catalysed by nanoparticles are ecofriendly and versatile methods for the sustainable synthesis of such fused heterocycles containing bioactive pyridine, pyrazole, phenazine, pyrimidine, pyran, imidazole, and relevant pyridine derivatives, possessing potential in medicinal and material chemistry. Full article

Wheat Fusarium crown rot (FCR), predominantly caused by Fusarium species, is a devastating fungal disease that severely threatens global wheat production. In this study, we combined phytopathological assays, molecular techniques, and bioinformatic analyses to systematically identify the causal agents of FCR in Xinjiang and to screen for potential biocontrol bacteria. A total of 296 fungal isolates were obtained from 195 FCR samples, collected from Yumin County and Xinhe County. Morphological and phylogenetic analyses revealed that Fusarium culmorum was the predominant pathogen, accounting for 73.6% of the total isolates. To evaluate the resistance of local wheat cultivars, F. culmorum XN22-1, a highly virulent strain from Xinhe County, was inoculated to 30 wheat varieties. The results demonstrated that most cultivars lacked resistance to FCR, with the exception of three varieties—Xinchun 19, Xinchun 50, and Youpi 23, which showed a mid-resistance. Given the scarcity of resistant cultivars, we focused on biological control. To control FCR, Pseudomonas aeruginosa J-7, exhibiting broad-spectrum antagonistic activity, was successfully isolated from rhizosphere soil based on the analysis of healthy rhizosphere soil microbial diversity. Subsequently, pot experiments showed that P. aeruginosa J-7 could significantly reduce the disease incidence and lower the disease index of wheat FCR. Furthermore, whole-genome sequencing, in-plate metabolite analysis, and observation on inhibition of spores and mycelium revealed that P. aeruginosa J-7 mediates its biocontrol activity primarily through the production of phenazine and siderophores, which collectively inhibit conidial germination and cause structural damage to the mycelium. This study not only clarifies the composition of FCR pathogens in Xinjiang but also provides a promising biocontrol agent and new strategic insights for the management of wheat crown rot. Full article

The crystal structures of the cobalt(II) metal–organic frameworks or coordination networks of [Co(pdb)(DMF)] and [Co₂(pdi)(DMF)₃]·2(DMF)·H₂O (H₂pdb = 3,3′-(phenazine-5,10-diyl)dibenzoic acid; H₄pdi = 5,5′-(phenazine-5,10-diyl)diisophthalic acid; DMF = N,N-dimethylformamide) were synthesized solvothermally from cobalt(II) nitrate and the free acid of the linker in DMF. Systematic solvothermal screening demonstrated strong metal- and counterion-dependent framework formation, as crystalline coordination polymers were obtained exclusively from cobalt(II) nitrate, whereas other metal salts and cobalt(II) chloride or sulfate produced no crystalline materials. In catena-[(N,N-dimethylformamide)-μ₄-3,3′-(phenazine-5,10-diyl)dibenzoate-cobalt(II)], [Co(pdb)(DMF)], the Co₂ units, acting as secondary building units, are coordinated by four carboxylate groups from four linkers in a paddle-wheel arrangement, giving a three-dimensional (3D) network with cds (or CdSO₄) topology, in which the wide openings are filled by two symmetry-related nets to form a threefold interpenetrated structure. In catena-[tris(N,N-dimethylformamide)-μ₈-5,5′-(phenazine-5,10-diyl)diisophthalate-dicobalt(II)] bis(N,N-dimethylformamide) hydrate, [Co₂(pdi)(DMF)₃]·2(DMF)·H₂O, there are two different Co atoms, of which only Co₂ is connected to each of the four carboxylate groups of the tetracarboxylate linker and, thus, is responsible for 3D network formation. The network topology in [Co₂(pdi)(DMF)₃] is pts (or platinum(II) sulfide) when taking the Co₂ atom as a tetrahedral node and the linker as a square-planar fourfold node; however, this arrangement is inverse to the common square-planar metal and tetrahedral linker nodes found in PtS and most pts topologies. Full article

Pseudomonas aeruginosa and Scedosporium/Lomentospora often coexist in the lungs of cystic fibrosis patients, where their interaction can affect disease outcomes. Our group has recently demonstrated that P. aeruginosa suppresses the growth of Scedosporium/Lomentospora species partly through mechanisms involving iron sequestration. In this study, we have investigated how molecules secreted by P. aeruginosa under high (36 µM) and low (3.6 µM) iron conditions affect the planktonic growth and biofilm formation by S. apiospermum, S. minutisporum, S. aurantiacum and L. prolificans. Although P. aeruginosa exhibited enhanced proliferation under high-iron conditions, spectrophotometric analyses revealed a marked increase in phenazine and pyoverdine production under low-iron conditions, with siderophore activity confirmed by Chrome Azurol S assays. Supporting these findings, supernatants from P. aeruginosa cells grown under iron limitation markedly inhibited fungal growth (≈30%) and biofilm formation (≈70%), whereas those from high-iron cultures were less effective. Notably, low-iron bacterial-free supernatants exhibited pronounced cytotoxic effects on mammalian cells, reducing metabolic activity by an average of 20% in A549 lung epithelial cells and 40% in THP-1 macrophages, and significantly compromising survival in the Tenebrio molitor infection model, resulting in 100% larval mortality within 7 days. Collectively, these results indicate that the antifungal activity of P. aeruginosa is closely coupled with increased host toxicity. Moreover, the results demonstrate that environmental iron availability plays a critical role in modulating both antifungal activity and toxicity, thereby shaping P. aeruginosa interactions with Scedosporium/Lomentospora species. Such iron-dependent dynamics may influence the progression and severity of respiratory co-infections, with important implications for patient management and therapeutic interventions. Full article

Biofilms are more than just structural microbial communities. They are dynamic chemical ecosystems that synthesize a range of extracellular compounds involved in functions that extend beyond biofilm architecture. From quorum-sensing molecules like acyl-homoserine lactones (AHLs) to short-chain fatty acids (SCFAs), phenazines, indoles, and reactive sulfur species (RSS), biofilm-derived metabolites can impact the physiology and behavior of microorganisms living in the same ecosystem, including other bacteria and protozoa. It has recently been demonstrated that such molecules may also modulate competition between microbes, promote cooperation, and impact motility, differentiation, or virulence of free-living and parasitic protozoa. This review aims to discuss biofilm compounds that mediate interspecies or interkingdom interactions and their involvement in regulating gut and environmental microbiomes functions, and host–pathogen relationships with special emphasis on protozoan activity and the infection outcome. This review will also address how this chemical dialog can be explored to identify new therapeutic interventions against microbial infections and parasitic diseases. Full article

Redox mediators are central to electrochemical biosensors, enabling electron transfer between deeply buried enzymatic cofactors and electrode surfaces when direct electron transfer is kinetically inaccessible. Among all design parameters, the reversibility of mediator redox cycling remains the most decisive yet under-examined factor governing biosensor stability, drift and long-term reproducibility. This review establishes reversibility as a unifying framework grounded in inorganic and organometallic redox chemistry, with particular emphasis on coordination environments, ligand-field effects and outer-sphere electron-transfer pathways. Recent advances (2010–2025) in ruthenium and osmium polypyridyl complexes, cobalt macrocycles, hexacyanoferrates and Prussian Blue analogues are examined alongside ferrocene derivatives and other organometallic mediators, which together define the upper limits of reversible behaviour. Organic mediator families, including quinones, phenazines, indophenols, aminophenols and viologens, are discussed as mechanistic contrasts that highlight the structural and thermodynamic constraints that limit long-term cycling in aqueous media. Mechanistic indicators of reversibility, including peak separation, current ratios and heterogeneous electron-transfer rate constants, are linked to mediator architecture, coordination chemistry and immobilisation environment. By integrating molecular electrochemistry with applied sensor engineering, this review provides a mechanistically grounded basis for selecting or designing redox mediators that sustain efficient electron transfer, minimal fouling and calibration stability across diverse sensing platforms. Full article

White-nose syndrome (WNS) is an infectious disease of bats caused by the psychrophilic fungus Pseudogymnoascus destructans. Phenazine-1-carboxylic acid (PCA) is a microbial secondary metabolite with broad-spectrum antifungal activity. Previous studies show that PCA suppresses the growth of P. destructans at low concentrations, yet its mechanism remains unclear. Here, we evaluated the in vitro antifungal activity of PCA. We then investigated its potential mechanism using physiological and biochemical assays, as well as integrated transcriptomic and metabolomic analyses. PCA showed effective antifungal activity against P. destructans (EC₅₀ = 32.9 μg/mL). Physiological and biochemical assays indicated that PCA perturbed cell wall organization and increased membrane permeability, leading to leakage of intracellular contents. It also induced oxidative stress, DNA damage, and apoptosis. Multi-omics integration revealed that PCA markedly perturbed cell wall and membrane metabolism, virulence factor expression, and energy metabolism. It provoked oxidative stress while downregulating genes involved in the cell cycle, DNA replication, and repair. Together, these findings delineate the inhibitory effects of PCA on P. destructans in vitro, provide initial mechanistic insights into its antifungal action, and suggest that PCA merits further evaluation as a possible component of environmentally compatible strategies for WNS management. Full article

Liquid chromatography–mass spectrometry analysis of Pseudomonas chlororaphis subsp. phenazini S1Bt23 extracts detected phenazine-1-carboxylic acid (PCA) and 2-hydroxyphenazine (2-OH-PHZ) as the main phenazine derivatives. We investigated their relative contributions to the antagonistic activity of strain S1Bt23 against Pythium arrhenomanes, a root rot pathogen of corn. CRISPR-Cas9 knockouts were carried out on the phzF gene, required for PCA synthesis, and the phzO gene, which is involved in converting PCA to 2-OH-PHZ. Deletion of the phzF gene abrogated the production of PCA and 2-OH-PHZ, and the ΔphzF mutant lost the antagonism against Pythium arrhenomanes. In contrast, deletion of the phzO gene created a 2-OH-PHZ-negative mutant with intact antagonistic ability. Concordantly, S1Bt23 wild type and the ΔphzO mutant, but not the ΔphzF mutant, significantly bioprotected corn seeds of a susceptible inbred variety, CO441, from P. arrhenomanes. At equimolar amounts of 75 nM, synthetic PCA inhibited Pythium growth, whereas 2-OH-PHZ did not. This highlights the critical contribution of PCA to the biocontrol activity of strain S1Bt23 against P. arrhenomanes. Unexpectedly, deletion of phzO did not result in additional PCA accumulation. This suggests that the conversion of PCA to 2-OH-PHZ by S1Bt23 is a potential protective mechanism against the overproduction of lethal cellular doses. This study paves the way for bioengineering strain S1Bt23 into a more effective biopesticide. Full article

Neutral red (NR) is a phenazine dye that has been implicated in electron transfer processes in methanogenic archaea. NR has been previously observed to enhance methane production but its effects on Methanosarcina barkeri are unknown. This study aimed to investigate the effects of NR on M. barkeri DSM-804. M. barkeri cultures were grown in the presence of 10 and 250 µM NR for four weeks, and proteomic analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that methane production was significantly reduced in the presence of NR, at lower concentrations of both 10 and 250 µM NR treatments, compared to the control. Proteomic analysis revealed the downregulation of proteins related to substrate metabolism and methanogenesis, such as the heterodisulfide reductase subunits D (HDRD_METBF) and E (HDRE_METBF), suggesting that NR hindered essential metabolic processes. Proteomic analysis also revealed that M. barkeri lacked methanophenazine in its membrane, which is a component essential for electron transport via neutral red (NR) that supports enhanced growth and methane production. Further research is needed to explore the role of methanophenazine and understand the mechanisms underlying NR’s effects of NR on methanogenesis in M. barkeri. Full article

Background/Objectives: Postbiotics derived from lactic acid bacteria are emerging as promising antimicrobial agents due to their antibacterial, antibiofilm, and immunomodulatory properties. Among their metabolites, lactic acid (LA) is thought to play a major role in antimicrobial activity. This study investigated the proteomic response of Pseudomonas aeruginosa and Staphylococcus aureus to Lacticaseibacillus rhamnosus cell-free supernatant (CFS) and compared it with that elicited by LA alone. Methods: Overnight bacterial cultures were exposed to sub-MIC LA or CFS (1:10 for P. aeruginosa and 1:8 for S. aureus; ~12.5–15.6 mM LA) for 6 h at 37 °C. Intracellular proteins were harvested and subsequently quantified and purified to be analysed by HPLC–MS/MS, for quantitative label-free proteomics. Results: Proteomic analysis revealed clear separation of treated samples from controls, with largely overlapping responses to CFS and LA. Hallmark acid-stress adaptations were observed, including urease-mediated pH buffering, confirming that part of the response was driven by mild organic acid. In P. aeruginosa, treatments suppressed virulence pathways (phenazines, T3SS), while shifting metabolism toward lactate utilisation and reinforcing the outer membrane (lipid A, polyamine). In S. aureus, decreased abundance of the SaeRS-regulated immune-evasion factor Sbi, together with changes in envelope, ROS and translation-related proteins, suggested a bacteriostatic-like state. S. aureus differences between CFS and LA were more pronounced; CFS uniquely increased cell-wall defences, oxidative stress (SodA, SodM) and chaperone expression (GroS, GrpE), suggesting stress beyond acidification alone. Conclusions: These findings shed light on the molecular mechanisms underlying bacterial adaptation to CFS and highlight their potential as a novel antimicrobial approach. Full article

A genomic analysis of the hydrocarbon-oxidizing strain R. qingshengii F2-2 was conducted to characterize the genes responsible for plant growth stimulation and phytopathogen biocontrol. Understanding these mechanisms is vital for developing effective phytoremediation approaches. It was shown that the F2-2 genome consists of a 6.3 Mb chromosome and three plasmids, two of which are linear—pLP156 (155 kb) and pLP337 (337 kb)—and one circular—pCP209 (210 kb). The genes responsible for biosynthesis of phytohormones (auxins, gibberellins, cytokinins), phosphate solubilization, and production of siderophores and antibiotic-active compounds (chloramphenicol and pristinamycin IA) were identified in the strain chromosome. Orthologous genes encoding phenazine antibiotics were found in the linear plasmid pLP156. The phytostimulating properties of the strain, associated with auxin production (2–4 μg/mL); the ability to effectively colonize rapeseed, mustard, and tobacco plants; and protective action against Fusarium spp. under artificial phytopathogenic background conditions, were experimentally confirmed. Thus, the discovered properties of the R. qingshengii F2-2 strain indicate its potential for the phytoremediation of oil-contaminated soils. Full article