Search Results (1,675)

Beyond their role as fishmeal replacements in aquafeeds, insects may enhance fish resistance to microbial diseases and improve feed shelf life through the presence of antibacterial compounds. This study evaluated the antibacterial activity of extracts from silkworm pupae (Bombyx mori, BM), larval meals of black soldier fly (Hermetia illucens, HI), mealworm (Tenebrio molitor, TM), and superworm (Zophobas morio, ZM), and adults of house cricket (Acheta domesticus, AD), two-spotted cricket (Gryllus bimaculatus, GB) and weaver ant (Oecophylla smaragdina, OS). The extracts were tested against ten Gram-negative marine bacterial pathogens associated with aquaculture disease outbreaks, as well as the Gram-positive bacterium, Bacillus thuringiensis. The antibacterial activity of aqueous and solvent-soluble extracts was assessed using agar diffusion assays, turbidimetric growth kinetics, and MTT metabolic assays. Several insect extracts exhibited moderate to strong antibacterial activity. In particular, the aqueous extracts of BM and GB, the methanolic extract of HI, and the isopropanolic extracts of HI and OS were effective against multiple bacterial strains, including strains with reduced susceptibility to the reference antibiotics bacitracin, oxolinic acid, and streptomycin. These findings highlight the potential of HI, GB and especially OS as functional ingredients or feed additives for aquaculture. Full article

Hemorrhagic pneumonia is a severe and often fatal disease in captive forest musk deer (Moschus berezovskii), but the pathogen remains incompletely understood. Based on incomplete statistics, the estimated incidence in captive populations ranges from 20% to 80%, with the disease occurring mainly in autumn, winter, and early spring. The disease has an acute onset and rapid progression. Due to the species’ strong stress response, affected animals rarely show behavioral changes, making early detection difficult. In this study, we investigated a mortality case presenting with oral bleeding and hematemesis on a forest musk deer farm. Postmortem examination revealed diffuse hemorrhagic pneumonia, and lung tissue samples were collected for histopathology, bacterial isolation, full-length 16S rRNA gene sequencing, and DNA/RNA virome sequencing. Histological examination showed extensive alveolar hemorrhage, fibrinous exudate, and macrophage infiltration. Bacterial culture and 16S rRNA gene sequencing identified Bergeyella zoohelcum as the predominant bacterium, accounting for 100% of the bacterial community in the lung tissue. Virome analysis revealed predominantly DNA bacteriophages (e.g., Cirlivirales, Cremevirales, Microviridae) and no known pathogenic RNA viruses; only seven low-abundance, unclassified RNA viral contigs of low completeness were detected. These results indicate that B. zoohelcum is the likely causative agent of hemorrhagic pneumonia in this case, with no evidence of viral involvement. This study provides the first direct association of B. zoohelcum with hemorrhagic pneumonia in forest musk deer, highlighting its pathogenic potential and the importance of monitoring this bacterium in captive populations. Full article

Tularemia is a zoonotic disease caused by the highly contagious bacterium Francisella tularensis, with rabbits, hares, and rodents considered as primary reservoirs. Clinical manifestations in humans can range from mild to life-threatening, depending on the mode of exposure (ingestion, inhalation, skin contact, injection, or tick bite), with high fever being a common feature. The primary aim of the present research was to evaluate the circulation of F. tularensis and the potential infection among wild boar (Sus scrofa) and red deer (Cervus elaphus) from the central region of Portugal. A total of 368 samples (including serum and organ samples) were collected from 184 wild boar and 184 red deer. For serological analysis, two commercially available enzyme-linked immunosorbent assay (ELISA) kits were used to detect immunoglobulin M (IgM) and G (IgG) antibodies to F. tularensis. Antibodies to F. tularensis (IgG and IgM) were detected in one adult male wild boar, corresponding to a seroprevalence of 0.54% (1/184, 95% confidence interval [95% CI]: 0.01–3.0%). No antibodies to F. tularensis were detected in red deer. Molecular detection by PCR was negative in the seropositive animal, in which submandibular lymph node, liver, and spleen samples were analysed targeting the 16S rRNA gene. These findings indicate exposure of wild boar to F. tularensis in central Portugal, suggesting a sporadic presence of the pathogen. Although no evidence of active infection was detected in the analysed tissues, the presence of seropositive individuals highlights the need for further investigation. Despite the very low seroprevalence observed, the zoonotic potential of F. tularensis supports the importance of continued surveillance within a One Health perspective. Full article

Background: Lipopolysaccharide (LPS) functions as a Toll-like receptor 4 (TLR4) agonist that triggers innate immunity; however, structural variations between pathogenic and commensal bacteria distinctly influence its immunostimulatory profile. This study evaluated the immunostimulatory activity of LPS derived from the commensal bacterium Hafnia alvei and explored its potential as an exploratory vaccine adjuvant. Methods: Cytokine induction was evaluated in immune cells across diverse host species, and receptor activation was assessed via reporter assays. To investigate in vivo immunogenicity and preliminary tolerability, H. alvei LPS was formulated into a prototype oil-in-water (O/W) emulsion utilizing ovalbumin (OVA) as a model antigen. Results: LPS from H. alvei strain BA2000346 exhibited immunostimulatory activity comparable to that of Escherichia coli, while inducing greater TNF-α expression than pathogenic Salmonella and Pseudomonas strains. Distinct from E. coli LPS, it demonstrated the capacity to activate both TLR4 and the mannose-recognizing Dectin-2 receptor in reporter systems. This cytokine induction was consistent across various strains and host species. Furthermore, the prototype O/W emulsion formulation enhanced antigen-specific humoral and cellular immune responses while demonstrating preliminary tolerability based on body-weight monitoring and visual clinical observation. Conclusions: H. alvei-derived LPS exhibits TLR4 and Dectin-2 agonist activity in vitro. When synergized with an O/W emulsion delivery system, it provides a preliminary indication of cross-species stimulatory potential and supports further investigation as a hypothesis-generating platform for future vaccine adjuvant development. Full article

The oral pathogen Filifactor alocis encodes a repeats-in-toxin (RTX) protein, FtxA, that is encoded by the ftxA gene; it is present in approximately 50% of known isolated strains from various infected oral sites, including periodontitis, peri-implantitis, and root canal infections. It has been determined from PCR assessment of periodontally diseased cohorts in Ghana and Australia. Based on current knowledge, ftxA appears to be associated with both the progress and severity of periodontitis. This finding could potentially be linked to enhanced levels of ftxA-positive F. alocis, relative to ftxA-negative strain, and/or, in addition, a synergy between ftxA-positive strains and other periodontal pathogens. The exact mechanism remains unclear but may depend on an FtxA-mediated shifting of the host cell response toward immunosuppression. The main objective of the present work was to evaluate the prevalence and loads of F. alocis and the presence of ftxA in subgingival plaque in patients recruited for periodontal treatment in Sweden. This observational study included all samples that were received from external clinics over one full year (n = 71 patients). Our findings revealed that F. alocis was carried by 49 (69%) of the individuals, with the prevalence of ftxA amounting to 42.9% (n = 21). In 32 of the 71 samples, F. alocis could be quantitatively assessed. In this sub-population of F. alocis-positive patients, high loads of the bacterium were not related to age, and high loads were more frequently observed upon carriage of ftxA. The presence of, and co-colonization with, F. alocis with four additional periodontal pathogens was also evaluated. F. alocis was notable in that it co-colonized with all of the other species. Moreover, it was detected alongside two and even three of the other species within the same sample. Full article

Listeria monocytogenes is a ubiquitous Gram-positive bacterium responsible for listeriosis, a foodborne zoonotic disease affecting humans and animals. Although infection in immunocompetent individuals is often asymptomatic or limited to mild self-limiting gastroenteritis, Listeria monocytogenes may cause severe invasive disease in vulnerable groups, including pregnant women, neonates, elderly individuals, and immunocompromised patients. Although the incidence of listeriosis is relatively low compared with many other foodborne pathogens, the high hospitalization and mortality rates associated with clinical cases make this bacterium a major concern for food safety and public health. The evolutionary success of L. monocytogenes reflects the interaction between a conserved core genome and a dynamic accessory genome shaped by horizontal gene transfer (HGT), ecological selection, and expansion of specific clones. Transient intestinal carriage in humans and animals, potentially influenced by gut microbiome composition, creates ecological interfaces where plasmids, transposons, prophages, and integrative conjugative elements contribute to the exchange of antimicrobial resistance determinants, virulence factors, and stress tolerance systems. Virulence diversification is further influenced by the differential distribution of pathogenicity islands such as LIPI-1, LIPI-3, and LIPI-4 across specific clonal lineages. These evolutionary processes occur across interconnected farm, food-production, environmental, and clinical ecosystems consistent with the One Health framework. Advances in whole-genome sequencing have clarified lineage-specific gene flow, expansion of specific clones, and the dynamics of the resistome and mobilome in L. monocytogenes populations. This narrative review aims to synthesize current knowledge on the mobile genetic elements and ecological interfaces that shape horizontal gene transfer in L. monocytogenes. Its novelty lies in integrating antimicrobial resistance, virulence-associated genomic islands, stress adaptation, and gut microbiome-mediated selection within a One Health and metapopulation framework. The main message of this review is that HGT should be interpreted as a context-dependent contributor to L. monocytogenes adaptation, acting together with clonal background, ecological selection, and mobile genetic elements. Full article

Biosurfactants are surface-active microbial molecules with increasing industrial relevance as sustainable alternatives to synthetic surfactants. Among them, lipopeptides produced by Bacillus species, particularly surfactin, exhibit strong interfacial activity and biological functionality. In this study, rhizospheric soils from the La Araucanía region, Chile, were explored as a source of biosurfactant-producing bacteria. Eighteen strains were isolated, and two high-performing strains, Solo 1 and Solo 4, were identified as Bacillus amyloliquefaciens and Bacillus subtilis, respectively. Both strains harbored the srfAA gene and produced surfactin isoforms confirmed by MALDI-TOF MS. Kinetic analysis revealed distinct production profiles, with Solo 1 reaching a maximum of 90 mg L⁻¹ at 24 h, whereas Solo 4 showed continuous production up to 224.4 mg L⁻¹ at 72 h. Both biosurfactants exhibited high emulsification capacity (>80%) and stability across wide ranges of temperature, pH, and salinity. Importantly, cell-free supernatants from both strains showed antibacterial and antibiofilm activity against Staphylococcus aureus, with Solo 4 reaching 81% biofilm inhibition. In addition, surfactin-enriched extracts inhibited the pathogenic bacterium Pseudomonas syringae and the filamentous fungus Fusarium oxysporum, with Solo 4 consistently showing stronger antimicrobial performance. Overall, these findings identify Solo 4 as a promising native Bacillus strain for future development of biosurfactant-based systems aimed at antimicrobial control, biofilm management, agricultural pathogen suppression, surface sanitation, and environmentally compatible biotechnological processes. Full article

Bacterial–fungal interactions are prevalent in microbial communities, and fungi often facilitate bacterial dispersal along networks created by fungal hyphae. Using a microfluidic device, we examined how diverse bacterial species disperse in monoculture versus travel in coculture with Aspergillus flavus. Most of the bacteria traveled further when in coculture, although this was not absolute. Two bacteria showing significant dispersal rates only in coculture were the human pathogens Listeria monocytogenes and Staphylococcus aureus. Mechanistically, L. monocytogenes dispersal required flagella, with dispersal impaired in flagellar mutants but enhanced in ∆mogR strains that upregulate flagellar expression. In contrast, the non-flagellar bacterium S. aureus exhibited a unique, wave-like dispersal pattern along the hyphae, a phenomenon that was abolished in agr quorum-sensing mutants deficient in phenol-soluble modulins (PSMs). In a triculture of L. monocytogenes, S. aureus, and A. flavus, L. monocytogenes limited S. aureus dispersal along the fungal hyphae; however, this inhibition was dependent on an intact L. monocytogenes quorum system. Our findings reveal that bacterial motility on fungal networks arises from diverse, species-specific mechanisms, including flagella, transcriptional regulation, potential quorum-sensing-mediated interactions, as well as other notable dispersal phenomena that warrant further investigation. Full article

Tamarindus indica L., a key economic tree species in tropical regions, suffers severely from postharvest decay. From 2023 to 2025, disease fruits exhibiting pericarp softening, pulp browning, and sticky exudates were collected in Yunnan, China. Pathogenicity tests following Koch’s postulates, combined with morphological characterization and phylogenetic analyses of the internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF 1α), and beta-tubulin (TUB) gene regions, identified the causal pathogen as Botryosphaeria fabicerciana (isolates ZWML-06, ZWML-44, ZWML-17). This is the first report of this postharvest disease on tamarind in Yunnan, filling an etiological gap. Additionally, an endophytic bacterium, designated BV-1, was isolated from asymptomatic pulp tissues. Whole-genome sequencing and phylogenetic analysis identified it as Bacillus velezensis. Strain BV-1 exhibited strong in vitro antagonistic activity against the pathogen, indicating promising biocontrol potential. Functional annotation revealed that BV-1 possesses a complex genetic system with developed transporter systems; its core metabolic network is dominated by nitrogen metabolism and redox processes, suggesting a potential “multi-target” antimicrobial mechanism. This study provides a theoretical basis and novel resources for the green control of postharvest diseases in tamarind. Full article

Fusarium solani is an emerging pathogen responsible for Fusarium-related diseases in durian trees in Thailand. Several chemical fungicides and biocontrol agents are ineffective in controlling these diseases, which affects durian trees and reduces yields. This study aimed to identify soil-derived bacteria with biocontrol activity against F. solani that surpasses traditional biocontrol bacteria. The characteristics and biocontrol efficacy of effective isolates were analyzed. Four isolates from 107 bacterial isolates were identified as effective biocontrol agents against F. solani. Isolate S301 exhibited the highest inhibition at 74.31%, exceeding that of the traditional biocontrol bacterium Bacillus subtilis. These isolates antagonized F. solani by producing siderophores, fungal cell wall lytic enzymes, and hydrogen cyanide, and by promoting plant growth. Molecular and phylogenetic analyses identified the four isolates as members of the Bacillus genus, specifically B. safensis, B. thuringiensis, B. subtilis, and B. cereus. The application of B. safensis strain S101 and B. subtilis strain S301 showed potential to reduce fungal disease symptoms on Monthong durian leaves. These findings are the first to demonstrate the potential of B. safensis and B. subtilis as promising bacterial biocontrol agents for managing F. solani-related diseases in durian trees in Thailand. Full article

Background: Root rot caused by Fusarium solani is a devastating disease in Angelica sinensis (danggui), leading to severe yield and quality losses. Sustainable control strategies are urgently needed. According to the plant “cry for help” theory, plants under pathogen attack may recruit beneficial microbes via root exudates. However, whether A. sinensis employs this strategy against F. solani remains unknown. This study aimed to identify potential “cry for help” metabolites and evaluate their biocontrol potential. Methods: LC-MS analysis revealed that F. solani infection significantly altered the metabolic profiles of both A. sinensis roots and rhizosphere soil. Results: Comparative analysis identified seven metabolites specifically upregulated in infected plants but not detected in the pathogen, including taurine, oxoadipic acid, quinolinic acid, 6-phosphogluconic acid, methyl cinnamate, 2-phenylethanol, and (R)-3-hydroxybutyric acid. Exogenous application of these seven metabolites revealed that taurine and methyl cinnamate significantly alleviated disease symptoms, improved plant growth (root length, biomass), and enhanced the activities of key defense enzymes (peroxidase, POD, phenylalanine ammonia-lyase, PAL, lipoxygenase, LOX, polyphenol oxidase, PPO). Furthermore, taurine and methyl cinnamate reshaped the rhizosphere microbiome. The incidence of root rot was reduced by 51.3% and 50.8%, respectively. Taurine enriched actinobacteria (e.g., Paeniglutamicibacter) and reduced the relative abundance of pathogenic Ascomycota fungi, while methyl cinnamate markedly enriched the nitrogen-fixing bacterium Azotobacter and the saprophytic fungus Schizothecium. Crucially, both treatments significantly suppressed the proliferation of F. solani in the rhizosphere. Conclusions: Our findings demonstrate for the first time that A. sinensis activates a “cry for help” response upon attack by F. solani, with taurine and methyl cinnamate preliminarily identified as key signaling metabolites that can directly or indirectly inhibit the development of A. sinensis root rot. These compounds enhance plant resistance and recruit beneficial microorganisms, offering a novel and promising ecological strategy for the green control of A. sinensis root rot. Full article

Background: Biofilms consist of complex microbial communities embedded in an extracellular matrix which confer resistance to the most used antimicrobial agents. Chronic wounds are often associated with burns, trauma, surgery, diabetes and peripheral vascular disease. They are characterized by a marked delay in wound healing favoring the development of microbial biofilms, which in turn further delay tissue regeneration. Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant staphylococci biofilms are found in chronic wounds, seriously hindering wound treatment. Vitreoscilla filiformis, a Gram-negative non-pathogenic filamentous bacterium, has been shown to improve atopic dermatitis by reducing S. aureus colonization and inducing antioxidant responses in the skin. Objectives: The aim of the present study was to evaluate the antimicrobial, anti-inflammatory, and regenerative activities of the V. filiformis supernatant (VFS). Methods: The effect of VFS on bacteria growth was assessed by microbial growth kinetics and biofilm formation and dispersal. Antioxidant potential was determined by DPPH-scavenging ability and reduction in intracellular reactive oxygen species (ROS). The regenerative properties were assessed by scratch assay. Results: V. filiformis VFS holds strong anti-biofilm activity against S. aureus, S. epidermidis and methicillin-resistant S. aureus (MRSA), acting during both biofilm formation and dispersion. The decrease in biofilm mass is accompanied by a significant increase in the planktonic form compared to the untreated cells. Moreover, VFS is characterized by an interesting antioxidant activity, as demonstrated by a cell-free DPPH assay and a neutrophil-based in vitro assay. In addition, VFS can stimulate tissue regeneration in human dermal fibroblasts and keratinocytes. Conclusions: The demonstration of anti-biofilm, antioxidant and regenerative properties of V. filiformis supernatant could be exploited for the treatment of biofilm-associated wound infections. Full article

The phytopathogenic bacterium Pectobacterium carotovorum (Pcc) infects a wide range of crop plants and causes substantial economic losses. The authors of this study previously demonstrated that the selenium–arabinogalactan nanocomposite (Se/AG NC) is capable of mitigating the negative effects of infection of soybean seeds with Pcc during germination and can influence physiological and biochemical factors in the seedlings. This study investigated changes in the membrane fatty acid (FA) profile of soybean seedlings grown under different treatments and in control using chromatography–mass spectrometry (CMS). The soybean seed treatments included the following: (1) infection by Pcc alone; (2) nanopriming with Se/AG NC alone; and (3) infection by Pcc followed by nanopriming with Se/AG NC. The infection was performed by soaking seeds in a bacterial suspension. Nanopriming was performed by placing the seeds in an aqueous solution of Se/AG NC (6.25 µg/mL) with a Se concentration of 0.000625%. Then, the seeds were germinated over 5 days in the darkness at 25 °C. The FA profile of soybean seeds was characterized by 13 FAs dominated by linoleic (LA), linolenic (LNA), oleic (OA), palmitic (PA) and stearic (SA) acids. Se/AG NC nanopriming had no influence on the FA profile of soybean seeds. A unique FA profile of soybean seedlings was demonstrated. It consisted of 18 FAs containing 12 to 20 carbon atoms. The following FAs were dominant in the control samples: PA (28%), LA (32.8%), LNA (18.6%), and SA (7.5%). Pcc infection of the seeds amplified the content of unsaturated FAs. Nanopriming of the seeds with Se/AG NC had an obvious influence on the seedling FA profile. Treatment of soybean seeds infected with Pcc using Se/AG NC caused weakening of the detrimental effects of the pathogen, while giving the possibility to maintain soybean seedlings’ FA profile at the control level. Transcript levels of the GmFAD8-2 gene encoding the membrane-bound omega-3 FA desaturase (FAD) were elevated for soybean seedlings after both Pcc and Se/AG NC seed treatment processes. The FA double-bond index (DBI) grew under the influence of seed infection and dropped under other treatments. Nanopriming of the seeds with Se/AG NC effectively reduced stress in Pcc-infected plants, as evidenced by analysis of the abscisic acid (ABA) content. Variations in the membrane FA composition under nanopriming with Se/AG NC may be one of the forms of its phytoprotective effect. Full article

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant pathogen for both hospital-acquired and community-acquired infections, characterized by its strong epidemic potential and high mortality rate, posing a severe threat to global public health. CRKP spreads widely across the globe through the horizontal transfer of plasmid-mediated resistance genes such as *blaKPC*, *blaNDM*, and *blaOXA-48*. The clinical treatment options for this bacterium are limited, and its resistance has been increasing year by year, urgently necessitating the development of new antimicrobial drugs or alternative strategies. In recent years, the CRISPR-Cas system has shown great potential in the diagnosis and treatment of CRKP, including rapid detection and identification, gene editing, antimicrobial strategies, and resistance inhibition. For instance, CRISPR-Cas12a/13a can be used for the rapid detection and identification of CRKP, while CRISPR-Cas9/Cas3 can target resistance genes to reverse the resistance of strains. With the advancement of delivery and biotechnologies, the CRISPR-Cas system is expected to become an important tool against drug-resistant CRKP. This review focuses on the application of the CRISPR-Cas system in the detection and treatment of CRKP, analyzing its technical advantages, limitations, and future development directions. Full article

Triplophysa siluroides, a unique species of plateau fish, holds significant economic value. However, its natural population has sharply declined due to overfishing and the construction of water conservancy projects. Investigating the various conditions necessary for its growth is a crucial prerequisite for successful artificial breeding. This study used Edwardsiella tarda as the pathogenic bacterium to determine the median lethal concentration following infection of T. siluroides, as well as to examine changes in tissues, organs, and gene expression. The study found that dead T. siluroides displayed symptoms such as abdominal distension, fluid accumulation, and a reddened anus, and the median lethal concentration of E. tarda for T. siluroides was calculated to be 1.00 × 10⁶ CFU/mL. Following infection with E. tarda, the liver, intestine, gills, spleen, and kidneys exhibited varying degrees of lesions. Transcriptome sequencing identified a total of 54,667 genes. Compared to the blank control group, 192 genes were downregulated and 125 genes were upregulated in T. siluroides infected with E. tarda. In contrast, after infection with the poly(I:C) viral mimic, 225 genes were downregulated and 436 genes were upregulated. This study determined the median lethal concentration of E. tarda for T. siluroides via intraperitoneal injection under laboratory conditions. The results may contribute to disease prevention and control in the breeding of T. siluroides, as well as inform future risk assessments of infection in aquaculture water bodies. Full article