Search Results (1,505)

The actinobacterial strain DEC002 was isolated recently from volcanic soils of Deception Island. Its taxonomic identity was resolved through a polyphasic strategy integrating morphology, physiological profiling, multilocus phylogeny, and genome-wide comparisons to resolve its identity. Concatenated core gene trees together with average nucleotide identity and digital DNA–DNA hybridization values place DEC002 within Actinacidiphila fildesensis with robust support. This is the first molecular confirmation of the species beyond King George Island and secures a second verified locality within the South Shetland Archipelago. Growth at low temperature with tolerance to moderate salinity indicates a psychrotolerant lifestyle. Cell-free supernatants inhibited representatives of foodborne Gram-negative and Gram-positive bacteria, including representatives of Enterobacteriaceae, Vibrio, Staphylococcus and Streptococcus. Genome analysis revealed enrichment in multiple biosynthetic gene clusters for nonribosomal peptides, polyketides, terpenes, and ribosomally synthesized and post-translationally modified peptides (RiPPs), supporting the biosynthetic potential of the strain. Functional annotations emphasize replication and repair modules, mobile element-associated proteins, helix–turn–helix regulators, and versatile transport systems, features coherent with cold stress and oligotrophic soils. Antibiotic susceptibility assays indicate a broad resistance phenotype under the experimental conditions tested, together with extracellular antimicrobial activity. These data refine the biogeography of A. fildesensis and indicate DEC002 as a credible Antarctic source of specialized metabolites with antimicrobial promise. Full article

Environmental DNA (eDNA) offers a promising, non-invasive approach for monitoring infectious agents in aquaculture. While molecular techniques for detecting shrimp pathogens are well established in host tissues, there is a lack of standardized protocols for pathogen detection from environmental samples using conventional PCR. In this study, we developed and validated a universal conventional PCR protocol for monitoring DNA from major viral and bacterial shrimp pathogens within pond water and sediment samples. The method was applied to two commercial shrimp farms in Mexico, where eDNA was extracted from field-collected water and sediment. Using published primer sets, we successfully amplified DNA sequences corresponding to six key pathogens—Infectious hypodermal and hematopoietic necrosis virus (IHHNV), Baculovirus penaei (BP), Monodon baculovirus (MBV), Shrimp hemocyte iridescent virus (SHIV), Candidatus Hepatobacter penaei (NHP-B), and Acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio spp.—in environmental samples. Sequencing of PCR amplicons confirmed 93–100% identity to previously reported pathogen strains, highlighting the method’s reliability. Pathogen detection rates varied by site, sample type, and date, with the percentage of positive samples ranging from 11.1% to 77.7%. Notably, this is the first report of SHIV DNA detection from environmental samples in the Americas, highlighting its value for pathogen surveillance even in the absence of documented outbreaks. This protocol offers a cost-effective and scalable tool for pathogen surveillance in shrimp aquaculture, enhancing early disease detection and contributing to improved biosecurity and risk assessment frameworks. Full article

Vibrio alginolyticus is a common pathogenic bacterium and can cause diseases in aquaculture animals. Lysine lactylation (Kla) is a novel post-translational modification (PTM) that has been confirmed to play critical roles in key biological processes. However, the modification landscape and functions of Kla in V. alginolyticus remain unclear. In this study, lactylation modification profiles of the bacterial pathogen V. alginolyticus were first systematically characterized; a total of 9308 lactylation sites on 2155 proteins were successfully identified. The lactylation of cAMP receptor protein (CRP) and triosephosphate isomerase (TPI) was verified by Co-immunoprecipitation (Co-IP) and Western blot to validate the lactylome data. Bioinformatic analysis of the Kla sites revealed 32 conserved sequence motifs surrounding the modified residues. Kla proteins were mainly involved in central metabolic pathways, including glycolysis/gluconeogenesis and ribosome biogen regulators were found to contain Kla modification sites. To investigate crosstalk among lysine acylations in V. alginolyticus, we integrated Kla, lysine acetylation (Kac), and lysine succinylation (Ksuc) profiles and identified 337 co-modified proteins and 5 co-modified sites. Additionally, phylogenetic analysis of Vibrio alginolyticus CobQ based on protein sequence alignment revealed no homology to the known delactylase CobB. Combined in vitro and in vivo functional validation identified VaCobQ as a candidate delactylase with potential NAD⁺-independent activity. This study establishes a lysine lactylation landscape in V. alginolyticus, providing a resource for exploring Kla functions in bacterial metabolism and its possible connections to virulence. Full article

Atmospheric particulate matter poses a high risk by carrying potentially toxic components such as polycyclic aromatic hydrocarbons (PAHs). The major sources of these potentially toxic compounds include traffic-related emissions and winter heating, implying the combustion of fossil fuels or biomass. Air pollution, especially chronic exposure, poses the most serious human health hazard in childhood, and several studies emphasise the importance of research on the potential impacts of air pollution in school environments. While indoor air quality studies are already available in Hungary, investigations on outdoor air pollution in school environments are missing. To fill this gap, in a medium-sized Hungarian town, Veszprém, six schools were selected to assess air quality in the outdoor environments where schoolchildren spend their breaks and have physical training. These schools represent different locations and conditions, from high-trafficked sites to suburban environments. Using resuspended dust samples, environmental quality was assessed based on PAH contents of the samples and ecotoxicity tests (Vibrio fischeri bacterial bioassay). Ecotoxicity of the samples moved in a wide range, from highly toxic to non-toxic. PAH measurements indicated considerable contamination in the case of one sample taken from a suburban area. Source apportionment demonstrated that winter heating is also an important pollution source. Full article

This study investigated the effects of dietary Bacillus cereus, administered alone or in combination with biofloc technology, on the growth performance, immune response, disease resistance, and intestinal microbiota of Litopenaeus vannamei. Shrimp fed diets supplemented with B. cereus, either directly or via biofloc systems, exhibited significantly increased final body weight and specific growth rate, together with a reduced feed conversion ratio compared with the control group. The expression levels of key hepatopancreatic immune-related genes, including lysozyme, prophenoloxidase, superoxide dismutase, Toll, immune deficiency, and Relish, were significantly upregulated in probiotic-associated treatments. Following challenge with Vibrio parahaemolyticus, cumulative mortality was markedly lower in all treatments involving B. cereus or biofloc compared with the control. Although alpha diversity indices were not significantly affected, beta diversity analysis demonstrated that supplementation frequency and delivery mode altered intestinal microbial community structure. The phyla Bacteroidota, Firmicutes, and Proteobacteria predominated across treatments, while members of Marinilabiliaceae and Shewanellaceae were enriched under probiotic-associated conditions, suggesting enhanced nutrient transformation potential. Co-occurrence network analysis further revealed increased microbial network complexity and positive interactions in probiotic and biofloc treatments, indicating improved community stability. These findings demonstrate that the synergistic application of B. cereus and biofloc technology enhances growth performance, immune capacity, and intestinal microbial resilience in intensive shrimp culture, and that supplementation strategy plays a critical role in optimizing probiotic efficacy. Full article

Non-O1/non-O139 Vibrio cholerae strains are widely distributed in aquatic environments worldwide and are increasingly recognized as potential reservoirs of antimicrobial resistance and virulence-associated determinants. In this study, we performed an integrated phenotypic and genomic analysis of 116 V. cholerae isolates collected in 2024 from environmental and clinical sources in Jiaxing, China, including 106 non-O1/non-O139 isolates, 9 O1 isolates, and 1 O139 isolate. Antimicrobial susceptibility testing showed that most isolates remained susceptible to β-lactam/β-lactamase inhibitor combinations, third-generation cephalosporins, carbapenems, and tigecycline, whereas resistance was more frequently observed for ampicillin, streptomycin, nalidixic acid, and ciprofloxacin. Based on the non-susceptibility criteria of Maitrakas et al., 19 of 116 isolates (16.4%) were classified as multidrug-resistant, whereas none met the definition of extensively drug-resistant. Genomic analysis identified diverse resistance determinants, including plasmid-mediated quinolone resistance genes (qnrVC variants) and quinolone resistance-determining region mutations in gyrA and parC. Virulence-associated genes showed heterogeneous distributions: core regulatory and hemolysis-related genes were highly prevalent, whereas classical cholera toxin genes were largely absent. Several accessory virulence factors, including the RTX toxin operon, chxA, ninth, and makA, were detected in subsets of isolates. Core genome multilocus sequence typing revealed substantial genetic diversity, with environmental and clinical isolates distributed across multiple lineages and showing no clear clustering by isolation source. Overall, these data demonstrate the diverse antimicrobial resistance, virulence-associated gene repertoires, and population structure of the Jiaxing V. cholerae collection, with particular relevance to the predominant non-O1/non-O139 population. Full article

Aquaponic systems are increasingly recognized as sustainable technologies for integrated fish and vegetable production. However, concerns remain regarding the potential internalization of human pathogens into vegetables grown in these systems. This study assessed the risk of pathogen internalization in lettuce leaves grown in aquaponic systems with Nile tilapia challenged with Escherichia coli or Vibrio cholerae. The system comprised nine fish tanks, eighteen hydroponic pipes, and eighty-one lettuce plants, with tanks assigned to three treatments. Samples of water, fish gut, fish blood, and lettuce leaves were collected. Microbiological analyses included selective culture, biochemical assays, and molecular identification. Although colonies consistent with E. coli and V. cholerae were recovered on selective media, molecular sequencing identified other bacterial species, including Aeromonas sp., Aeromonas caviae, Aeromonas veronii, Enterobacter hormaechei, and Citrobacter freundii. The findings indicate that conventional culture-based methods may produce false-positive results and highlight the importance of molecular confirmation. Notably, pathogenic bacteria associated with tilapia were detected and appeared capable of disseminating through the system and internalizing into lettuce tissues. This result highlights the need for biosecurity measures, contamination monitoring, and the combined use of conventional and molecular diagnostic tools to ensure accurate pathogen detection and compliance with international food safety standards. Full article

Background: Disease outbreaks remain a major constraint on aquaculture production, making vaccination essential for disease management in farmed fish. However, injectable oil-adjuvanted vaccines can be costly and may induce adverse inflammatory reactions and welfare concerns, motivating investigations into alternative injectable adjuvant materials. Methods: We conducted an in vivo safety evaluation of shear-thinning, amidated TEMPO-oxidized cellulose nanofiber (TO-CNF) hydrogels formulated with an inactivated Vibrio anguillarum bacterin. Formulations were administered intraperitoneally to Atlantic salmon (Salmo salar L.) using a common garden design with cohabitated treatment groups across triplicate tanks. Fish were monitored and sampled at pre-injection baseline and at 300-, and 600-degree days post-injection. Safety endpoints included mortality, macroscopic and histopathological outcomes, and growth evaluated relative to sham controls, unmodified TO-CNF, and a commercial oil-adjuvanted vaccine. Results: Amidated TO-CNF formulations were associated with increased mortality (up to 16–18% in higher reagent-loading groups) compared to commercial oil-adjuvanted vaccine, material, and sham controls. Affected fish exhibited adverse outcomes, including adhesions, proliferative lesions, ascites, edema, hemorrhage, and secondary opportunistic infections. In contrast, controls showed minimal mortality and pathology. Growth and immune response endpoints were variable and did not demonstrate consistent treatment-associated effects. Physicochemical analyses indicated differences in formulation stability and qualitative compositional differences across modification levels, but these were not quantified nor linked to specific causal mechanisms in this study. Conclusions: The amidated TO-CNF formulations tested here were associated with formulation-dependent safety risks under the conditions evaluated and are not yet suitable as injectable vaccine adjuvants in Atlantic salmon. These findings define important safety constraints for this material class and highlight the need for improved modification and purification strategies. More broadly, this work underscores the importance of establishing in vivo safety boundaries prior to efficacy optimization for emerging biomaterial-based vaccine adjuvants. Full article

Water-soluble pectin (WSP) is a soluble dietary fiber with a high esterification degree and certain viscosity and emulsifying properties. It has diverse bioactivities—including antioxidant, anticancer, and anti-inflammatory properties. This study aimed to investigate the in vitro antioxidant mechanisms of water-soluble pectin, and the in vivo effects of intestinal antioxidant capacity and gut microbiota composition in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). In an experiment involving feeding fish with WSP added to the diet, the addition of 600 mg/kg WSP promoted the activities of CAT, SOD, and GSH-Px in the grouper intestinal tract, thereby enhancing the antioxidant properties. At the phylum level, the relative abundance of Actinomycetes and Armatimonadetes decreased significantly. At the genus level, the relative abundance of Vibrio and Subdoligranulum increased significantly. In addition, antioxidant genes, inflammatory factor genes, immune genes, apoptosis genes, and genes of specific transmembrane proteins may participate in the regulation and improvement of the hybrid grouper intestinal tract. (CAT, MnSOD, and GPX), (TNF-α, IL-β, IL-6, and TGF-β), (MHC2, TLR3, KEAP1, and IKK-α), (C3, C8, C9, and P53), and (Claudin-3a, Occludin, ZO-1, and ZO-3) may regulate the intestinal function of hybrid grouper. Therefore, adding an appropriate volume of WSP to the diet is beneficial for the intestinal health of hybrid groupers. Full article

Silver nanoparticle (AgNP)-based products have been increasingly applied in aquaculture due to their antimicrobial properties and capacity to modulate host immunity. This study investigated the biological activities of synthesized silver nanowires (AgNWs), with particular emphasis on their anti-Vibrio efficacy and immunomodulatory effects, to evaluate their potential application in shrimp aquaculture. Antibacterial activity was assessed using nonlinear regression analysis to determine minimum inhibitory concentrations (MICs) against three major Vibrio pathogens, while cytotoxicity and immune responses were evaluated using white shrimp hemocytes through cell viability assays and in vitro gene expression analysis, respectively. AgNWs exhibited antibacterial effects on Vibrio parahaemolyticus, Vibrio alginolyticus, and Vibrio harveyi, with MIC values of 873.7, 58.78, and 672.1 μg/mL, respectively. Hemocyte viability remained above 90% at AgNW concentrations of up to 1000 mg/L, indicating good biocompatibility. AgNWs significantly upregulated immune-related lipopolysaccharide and β-1,3-glucan-binding protein (LGBP) and Toll gene expression at specific concentrations, indicating immunostimulation. These results suggest that AgNWs possess antibacterial activity and immunomodulatory potential with low cytotoxicity, supporting their promise as a novel functional agent for shrimp disease management. Full article

To address the issues of operational complexity, long duration association, and reliance on specialized equipment with existing detection methods for Vibrio parahaemolyticus, this study established a rapid detection method for V. parahaemolyticus in exported aquatic products based on the domestically developed Enzymatic Recombinase Amplification (ERA) technology. To target the thermolabile hemolysin gene (tlh) and the iron-regulated virulence regulatory protein gene (irgB) of V. parahaemolyticus, highly specific ERA primers and probes were designed and screened. Two detection platforms, a colorimetric method and a fluorescent method, were developed. Method validation results showed that this detection system achieved specific amplification for all 30 tested V. parahaemolyticus strains, with no cross-reactivity observed with 30 other common foodborne pathogenic bacteria. The detection sensitivity for both the fluorescent and colorimetric methods reached 10⁻¹ ng/μL, with a minimum detection limit of 10 CFU/25 g for artificially contaminated samples. The entire detection process, including sample preparation, requires only approximately 20 min—significantly faster than traditional culture (24–72 h) or even conventional PCR methods. Collaborative validation across five independent laboratories confirmed excellent reproducibility, with inter-laboratory agreement yielding a Kappa coefficient of 0.98. The ERA method operates at a low, constant temperature (37–39 °C), eliminating the need for thermal cyclers. When combined with portable isothermal amplification devices and visual (colorimetric) readout, it offers a distinct advantage in terms of speed, cost-effectiveness, and suitability for resource-limited or field settings compared to existing PCR-based or culture-based platforms. This method is simple to operate, rapid, sensitive, and highly suitable for on-site application, providing a reliable and practical technical solution for the rapid screening and risk monitoring of V. parahaemolyticus in exported aquatic products. Full article

Fish host complex intestinal bacterial communities that contribute to a wide range of functions, from nutrient assimilation to modulation of the immune system. Understanding how environmental and host-related factors shape the fish gut microbiota is essential for advancing sustainable aquaculture practices. This study compared the intestinal microbiota of gilthead sea bream (Sparus aurata) between wild and aquaculture populations in western Greece using 16S rRNA gene amplicon sequencing targeting the V3–V4 region, combined with culture-based methods. The analysis was based on a 97% similarity threshold and included 141 gastrointestinal samples of fish collected at two aquaculture facilities and two wild fisheries, representing two different growth phases (150 g and 300 g body weight). High-throughput sequencing data revealed a clear separation of gut microbial communities according to origin (wild vs. aquaculture), geographic location, and body growth phase, with most wild fish groups exhibiting higher microbial diversity than their farmed counterparts, except for group MES_150 which showed similar or lower values. The gut microbiota was dominated by Pseudomonadota (53%), Bacillota (29%), Actinomycetota (7%), Deinococcota (5%), and Bacteroidota (4%). A shared core microbiome, comprising Psychrobacter, Staphylococcus, Geobacillus, Aeromonas, Enterobacter, Pantoea, Bacillus, and Acinetobacter, was detected across all populations. Wild fish were enriched in Psychrobacter, Aeromonas, and Photobacterium, while aquaculture fish displayed higher abundances of Vibrio, Allomeiothermus, and Staphylococcus. Network analysis revealed mostly mutually exclusive interactions in both groups but distinct patterns of co-occurrence, driven mainly by Paenibacillus, Enterobacter, and Staphylococcus in wild samples, and by Vibrio, Aeromonas, and Pseudomonas in farmed fish. Culture-based assays demonstrated greater diversity in wild fish, dominated by Pseudomonas, Staphylococcus, and Vibrio strains, in contrast to the frequent occurrence of Staphylococcus and Psychrobacter in aquaculture samples. The findings suggest that aquaculture practices significantly alter gut microbial community structure and reduce diversity, with potential implications for fish health and disease resistance. The identified core and differentially abundant taxa provide candidates for probiotic development to improve aquaculture sustainability. Full article

The sodium–galactose cotransporter from Vibrio parahaemolyticus (vSGLT) was first cloned and functionally characterized by the laboratory of Ernest M. Wright in 2000, establishing a one-to-one Na⁺:sugar coupling stoichiometry and pioneering a bacterial model for human SGLTs. Here, we revisit vSGLT using solid-supported membrane electrophysiology on the Nanion SURFE²R N1, providing a modern, non-radioactive kinetic analysis of Na⁺-coupled sugar transport. Rapid transient currents were observed upon substrate application to proteoliposomes containing purified vSGLT. D-galactose elicited the largest Na⁺-dependent responses, followed by D-glucose and D-fucose, while no transport was observed in K⁺-based solutions. Apparent kinetic parameters recapitulate the overall trends observed in the original radiolabeled uptake assays, with K_m(Na⁺) ≈ 18 mM and K_m(gal) ≈ 9.8 mM. These findings validate the SURFE²R N1 SSM system as a quantitative, label-free method for Na⁺ symport characterization and demonstrate that vSGLT retains its canonical substrate selectivity and stoichiometry. Full article

Almond hulls and shells are abundant by-products of the almond industry that could be valorized as bio-based absorbent polymers (BAP), offering a promising alternative to synthetic materials to improve water management in the agricultural setting. In this study, almond hulls and shells were pelletized in different proportions to assess pelletization feasibility and physical properties, followed by industrial-scale production of an industrialized formulation (80% hulls, 20% shells). Ecotoxicological risk was assessed using direct bioassays with whole pellets (germination with Lactuca sativa and Zea mays; acute toxicity with Eisenia fetida) and indirect bioassays with pellet water extracts (germination with L. sativa, immobilization with Daphnia magna, and bioluminescence inhibition with Vibrio fischeri). Field trials were conducted in an irrigated almond orchard to evaluate soil moisture dynamics and plant water status under different BAP application rates and irrigation regimes. Pelletization increased the soil’s water-holding capacity in the laboratory test and soil moisture in the field, even under reduced irrigation. However, ecotoxicological assays revealed significant to high acute toxicity at higher concentrations, depending on the organism and exposure pathway. Almond hull and shell pellets show potential to improve soil water retention and reduce irrigation demand but require cautious application and further testing to mitigate ecotoxicological risks. Full article

Vibrio alginolyticus is a foodborne pathogen commonly found in seafood and freshwater products, causing human illness through the consumption of tainted seafood. Small non-coding RNAs (sRNAs) take effect on the stability and translation of their target mRNAs by base-pairing, thereby quickly altering bacterial physiology and pathogenicity at the post-transcriptional level. This work constructed a label-free in-frame deletion mutant and a complement strain of micX, a cell-density-associated sRNA in V. alginolyticus. The ΔmicX mutant exhibited reduced growth and a reduction in the synthesis of exopolysaccharides, biofilm, and alkaline serine protease. A TMT-based quantitative proteomic analysis comparing ΔmicX with the wild-type strain identified 900 differentially expressed proteins, comprising 376 that were upregulated and 524 that were downregulated. The upregulated proteins are primarily associated with porin activity, transmembrane signaling receptor function, and the two-component system. The downregulated proteins are mainly engaged in processes including biofilm formation, cellular communication, and transmembrane transport activity. Of note, the expression levels of proteins involved in the type VI secretion system, exopolysaccharide synthesis, mannose-sensitive hemagglutinin type IV pili (MSHA), and biofilm formation were significantly reduced in the absence of micX. Furthermore, the expression levels of proteins associated with quorum sensing (particularly LuxR and AphA) changed significantly in the ΔmicX vs. WT comparison. These findings strengthened comprehension of the novel sRNA regulatory network and established a theoretical foundation for additional investigations into the virulence of V. alginolyticus. Full article