Canadian journal of microbiology最新文献

{"title":"Role of cold shock protein CspA in <i>Aeromonas salmonicida</i> subsp. <i>salmonicida</i> physiology and virulence.","authors":"Ahmed Hossain, Hajarooba Gnanagobal, Trung Cao, Ignacio Vasquez, Javier Santander","doi":"10.1139/cjm-2025-0118","DOIUrl":"10.1139/cjm-2025-0118","url":null,"abstract":"<p><p>Cold shock proteins are small, highly conserved nucleic acid-binding proteins that help bacteria adapt to stress conditions. <i>Aeromonas salmonicida</i> subspecies <i>salmonicida</i> is a psychotropic, Gram-negative intracellular fish pathogen that causes furunculosis in fish. The role of cold shock proteins in the stress response in marine pathogens like <i>A. salmonicida</i> is unknown. In this study, we reported the role of cold shock protein A (CspA) in <i>A. salmonicida</i> physiology, stress response, and virulence in lumpfish (<i>Cyclopterus lumpus</i>). <i>Aeromonas salmonicida</i> Δ<i>cspA</i> was characterized using phenotypic tests and transcriptomics. <i>Aeromonas salmonicida</i> Δ<i>cspA</i> showed a reduction in survival at low temperatures (0 and 4 °C) and in ox bile-containing (5%) conditions. Differential gene expression analysis showed 632 dysregulated genes in Δ<i>cspA.</i> Among these 632 differentially expressed genes (DEGs), 413 were upregulated, and 219 were downregulated. Most downregulated genes were related to the type III secretion system (T3SS). However, <i>A. salmonicida</i> Δ<i>cspA</i> was not fully attenuated in the lumpfish host but delayed fish mortality and reduced tissue colonization after systemic infection in contrast to the wild type strain. Overall, this study provides novel insight into the roles of CspA in virulence and the physiology of <i>A. salmonicida</i>.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-17"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147347297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of metals as antimicrobials: knowledge gaps and future directions.","authors":"Raymond J Turner","doi":"10.1139/cjm-2025-0316","DOIUrl":"10.1139/cjm-2025-0316","url":null,"abstract":"<p><p>We now find ourselves in the antimicrobial resistance era, where antibiotic-resistant bacteria are of increasing concern, leading to a need for new and novel antimicrobial agents. Unfortunately, interest in developing new antibiotics in the pharmaceutical industry has dwindled over the decades. Regardless, academic researchers over the past decade have made strides in exploring alternative options, and out of this, we see the field revisiting historical infection control agents. From this, we now see a field of research exploring the efficacy of metal-based antimicrobials (MBAs) and metalloantibiotics. These antimicrobial agents are formulated as metal salts, alloys, metal complexes, organometallics, and nanomaterials. Many effective formulations have been developed for various applications in which metals are used as antimicrobials that are effective against antibiotic-resistant strains. This critical opinion focuses on the use of metal salts as antimicrobial and antibiofilm treatments. The review identifies potential misinterpretations of mechanisms, knowledge gaps, areas that have been overlooked, and potential ideas to move forward. The goal here is to understand the challenges of dissecting the primary and secondary modes of action of MBAs to formulate effective antimicrobials containing metal elements. Finally, parameters that metal formulations must meet to become successful treatments without falling to the same fate as antibiotics are suggested.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-12"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147670680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Shewanella oncorhynchi</i> isolated from a recirculatory aquaculture system (RAS) in Alberta, Canada.","authors":"Xiaoji Liu, Calvin Ho-Fung Lau, Natalia Lorenc, David Rolland, Scott Hrycauk, Jennifer Ronholm","doi":"10.1139/cjm-2025-0173","DOIUrl":"https://doi.org/10.1139/cjm-2025-0173","url":null,"abstract":"<p><p>Certain <i>Shewanella</i> spp. cause spoilage of seafood. However, <i>Shewanella</i> from fish production facilities in Canada have not yet been characterized. In our study, we first isolated <i>Shewanella oncorhynchi</i> S23-S33 (S2-3) from the water in a rainbow trout tank from a recirculating aquaculture system (RAS) facility located in Alberta, Canada. Later we found another strain (FD-1) from the biofilters from the same facility. Whole genome sequencing revealed that both strains possess gene clusters for the biosynthesis of eicosapentaenoic acid and we confirmed the production in FD-1 by gas chromatography. Phylogenetic analyses showed the close relatedness of FD-1 and S2-3 to <i>S. oncorhynchi</i> S-1. Rainbow trout filets inoculated with FD-1 turned brown in colour compared to uninoculated. However, when we inoculated retail pink salmon (<i>Oncorhynchus gorbuscha</i>) with either FD-1 or S2-3, we did not observe the brown colour change. The storage time had a significant (<i>P</i> < 0.0001) impact on the lightness (L^*), red/green (a^*), and yellow/blue (b^*) of pink salmon. In summary, our research note records the preliminary characterization of <i>Shewanella</i> from a RAS trout facility in Alberta, Canada.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":"72 ","pages":"1-8"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145932306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The infection-exclusive proteome of murine extracellular vesicles defines <i>Klebsiella pneumoniae</i>-induced immune response signatures.","authors":"Effie Honeywell, Brianna Ball, Arjun Sukumaran, Benjamin Muselius, Gisela Ströhle, Huiyan Li, Jennifer Geddes-McAlister","doi":"10.1139/cjm-2025-0043","DOIUrl":"10.1139/cjm-2025-0043","url":null,"abstract":"<p><p>Extracellular vesicles (EVs) are small, lipid bi-layered structures released from various cell types throughout the body. These structures are responsible for the delivery of proteins, compounds, and communication signals across spatial distances. EVs are highly important to diverse biological processes within mammalian systems, including roles in cellular maintenance and homeostasis of physiological conditions and response to infection, and they have the potential to serve as diagnostic hallmarks of infection. Despite these advances and promise, knowledge of the dynamics of EV production and composition during bacterial infection is limited. In this study, we characterize phenotypic traits and proteome remodeling of host EVs derived from murine models during a state of infection by the bacterial pathogen, <i>Klebsiella pneumoniae</i>, compared to an uninfected control. Phenotypic profiling defines consistent size, diameter, and number of EVs from samples across infectious states, whereas a closer look into molecular regulation at the protein level defines core and infection-exclusive proteomes. Within the core proteome (i.e., protein detection common between plasma from uninfected vs. infected samples) clustering based on infectious state was observed and significant increase (<i>p</i> < 0.01) in fibrinogen production upon infection were reported. Conversely, assessment of the infection-exclusive EV proteome supported detection of EVs by Gene Ontology Cellular Component classification revealed an enrichment of proteins associated with blood microparticles, membrane-bound, and the extracellular region, and highlighted the production of immune-associated proteins classified by Gene Ontology Biological Processes. Overall, this study emphasizes complex reprogramming of the host EV proteome upon exposure to <i>K. pneumoniae</i> within a murine model of infection and proposes protein-level signatures indicative of bacterial infection.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-13"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145997369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"No evidence of influenza A virus infection in marine mammals stranded in Basque Country coast (Northern Spain) in the context of H5N1 clade 2.3.4.4b expansion.","authors":"Ane López-Morales, Denis Benito, Xeider Gerrikagoitia, Vega Alvarez, Xabier Lekube, Urtzi Izagirre, Manu Soto, Jose Luis Lavín, Marta Barral","doi":"10.1139/cjm-2025-0211","DOIUrl":"10.1139/cjm-2025-0211","url":null,"abstract":"<p><p>Influenza A infection is frequently detected in marine mammals causing mortality events of different magnitude. In recent years, the highly pathogenic avian influenza (HPAI) H5N1 virus (clade 2.3.4.4b) has been rapidly expanding and infecting a new variety of avian and mammalian species, including marine mammals. Given this new epidemiological context, the objective of this work was to evaluate the influenza A virus infection of marine mammals stranded on the Basque Country coast. 38 marine mammals were studied (2012-2024), most of them (79%) being dolphins (striped dolphin, common dolphin, and common bottlenose dolphin). At necropsy, samples were collected from lung, intestine, and central nervous system when possible. During 2024, serum samples and oropharyngeal, nasal, and faeces/rectum swabs were also collected. Real-time RT-qPCR was applied for influenza A virus detection in tissue and swab samples, and commercial enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against influenza A viruses. All samples tested negative by PCR and ELISA. Despite the negative results obtained, we consider the continuation of the monitoring of influenza viruses in marine mammals essential by establishing collaboration networks and standardized protocols that allow us to gain insight into the epidemiology of influenza viruses in these species.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-6"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147347349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Successional stages and inferred functional profiles of bacterial communities under biocrusts in post-mining ecosystems of Western Boreal Quebec.","authors":"Gabriel F Peñaloza-Bojacá, Laura Hjartarson, Marta Alonso-Garcia, Juan Carlos Villarreal Aguilar, Line Rochefort, Mélina Guêné-Nanchen","doi":"10.1139/cjm-2025-0090","DOIUrl":"10.1139/cjm-2025-0090","url":null,"abstract":"<p><p>Mine tailings are inhospitable to plant establishment because of substrate instability, nutrient limitation, heavy metals, and temperature fluctuations at the soil surface. Biological soil crusts (biocrusts) and their associated microbial communities can initiate primary succession and facilitate plant-soil interactions, thereby supporting ecosystem recovery. Here, we characterized soil bacterial communities beneath biocrusts along a successional gradient in abandoned and rehabilitated molybdenum-bismuth mine tailings in Western Boreal Quebec. We collected 125 soil samples from bare soil, cyanobacterial-, chlorolichen-, and bryophyte-dominated biocrusts, as well as from a mixed bryophyte-lichen cover layer. Bacterial communities were assessed using amplicon sequencing (16S rRNA and nifH genes) and linked to soil physicochemical properties to infer functional potential. Soil pH, electrical-conductivity, and sulfur content were associated with bacterial diversity (distance-based redundancy analysis, <i>R</i>² = 0.20, <i>p</i> < 0.01). Rehabilitated sites exhibited moderate relative abundances of Proteobacteria (6.9%), whereas Actinobacteriota prevailed in nutrient-poor abandoned sites (17.1%), consistent with oligotrophic adaptation. Additionally, functional potential from chemoheterotrophy in later stages was associated with sulfur-oxidation (Spearman's <i>ρ</i> = 0.6, <i>p</i> < 0.05), with anoxygenic photoautotrophs potentially contributing to sulfur oxidation. Overall, our study indicates that bacterial communities may contribute to soil stabilization and could serve as key bioindicators of restoration success.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145997359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Note of appreciation.","authors":"","doi":"10.1139/cjm-2025-0292","DOIUrl":"https://doi.org/10.1139/cjm-2025-0292","url":null,"abstract":"","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":"72 ","pages":"1"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145910550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plant compartments and regional variations shape the community structures and functional composition of endophytic fungi of <i>Citrus aurantium</i>.","authors":"Zhongxiang Huang, Jianping Ou-Yang, Zhiqing Zhou, Hui Sun, Lingjue Wang, Ye Chen, Gang He, Yan Zhang","doi":"10.1139/cjm-2025-0237","DOIUrl":"10.1139/cjm-2025-0237","url":null,"abstract":"<p><p>Although <i>Citrus aurantium</i> has enormous medicinal and ecological value in southern China, little research has been conducted into the composition and functions of endophytic fungi in it. To better explore the characteristics of the endophytic fungal community in <i>C. auranti</i><i>um</i>, ITS rRNA gene analyses were used to characterize the endophytic fungal microbiome across three plant compartments and three regions. The results showed that a total of 12 109 OTUs were obtained and further divided into 15 phyla and 768 genera. Ascomycota was the dominant phylum. <i>Fusarium, Alternaria, Mortierella, Plectosphaerella, Cladosporium, Colletotrichum, Trichomerium, Botryotrichum</i>, and <i>Aspergillus</i> were the dominant genera. The endemic and dominant genera of endophytic fungi in <i>C. aurantium</i> exhibited plant compartment specificity. The assembly of endophytic fungal communities was dominated by homogeneous selection of deterministic processes. The endophytic fungal genera of <i>C. aurantium</i> predominantly exhibited positive interactions (with a proportion > 99%). The dominant functions of endophytic fungi in <i>C. aurantium</i> were pathotroph and saprotroph. The composition (niche: <i>R</i>²= 0.09, <i>P</i> = 0.001; site: <i>R</i>²= 0.06, <i>P</i> = 0.021) and functional components (niche: <i>R</i>²= 0.117, <i>P</i> = 0.002; site: <i>R</i>²= 0.122, <i>P</i> = 0.006) exhibited significant plant compartment and region specificity. The results of this study reveal the characteristics of the endophytic fungal community of <i>C. aurantium</i>, and provide a theoretical reference for the further development and utilization of endophytic fungal resources.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-13"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145687045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phenotypic profiling supports that <i>Listeria costaricensis</i> lacks in vitro pathogenicity but exhibits persistence traits.","authors":"Cristian Mata-Salazar, Olga Rivas-Solano, Victor Castro-Gutiérrez, Alejandra Huete-Soto, Mauricio Redondo-Solano","doi":"10.1139/cjm-2025-0216","DOIUrl":"10.1139/cjm-2025-0216","url":null,"abstract":"<p><p><i>Listeria costaricensis</i> was recently isolated from a food-processing facility. However, its pathogenic potential and persistence capacity remain poorly characterized at the phenotypic level, raising concerns about food safety. Therefore, we assessed its pathogenic potential through phenotypic invasion and adhesion assays in HeLa cells, showing that <i>L. costaricensis</i> cannot invade HeLa cells despite displaying a cell adhesion capacity comparable to that of <i>Listeria monocytogenes</i> and <i>Listeria innocua</i> reference strains. Given the industrial origin of the strain, we further evaluated its susceptibility to commonly used disinfectants by broth microdilution, finding susceptibility to a mixture of quaternary ammonium compounds (MIC < 100 µg/mL), and reduced susceptibility to peracetic acid (MIC > 160 µg/mL) and sodium hypochlorite (MIC > 500 µg/mL). Considering its demonstrated adhesion capacity, we assessed its ability to form biofilms on polystyrene surfaces, reporting a weak biofilm-forming phenotype comparable to other <i>L. monocytogenes</i> strains. Finally, using the VFanalyzer platform we identified on the <i>L. costaricensis</i> genome 28 virulence-associated gene sequences related to regulatory and structural functions, adherence, and an incomplete invasion gene group compared to <i>L</i>. <i>monocytogenes</i> strains. Collectively, these findings phenotypically support the previously proposed non-pathogenic nature of <i>L</i>. <i>costaricensis</i>, while also revealing a level of persistence comparable to other <i>L. monocytogenes</i> isolates.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-12"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145687100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global population genetics and evolutionary dynamics of <i>Candida albicans</i>.","authors":"Jezreel Dalmieda, Jianping Xu","doi":"10.1139/cjm-2025-0248","DOIUrl":"10.1139/cjm-2025-0248","url":null,"abstract":"<p><p><i>Candida albicans</i> is a common commensal yeast and an opportunistic pathogen of global health importance. However, its global geographic and temporal patterns of genetic variation remain poorly understood. Here we analyzed sequence data on seven housekeeping loci from >5000 isolates in the <i>C. albicans</i> PubMLST database representing >60 countries and spanning >70 years. Diploid sequences at each locus were phased into haplotypes to provide higher-resolution insights into diversity, differentiation, and recombination. Our analyses revealed high allelic and genotypic diversities within most geographic and temporal populations. Pairwise FST estimates revealed low but statistically significant differentiation among both geographic and temporal populations, with AMOVA revealing that most genetic variation resides within rather than among subpopulations. STRUCTURE analysis identified two genetic clusters but with extensive admixture within most geographic populations, consistent with frequent gene flow. Phylogenetic and haplotype network analyses revealed evidence of clonal expansion, with globally distributed haplotypes being genetically closer to one another than among more localized haplotypes. Finally, recombination analyses revealed evidence of non-random recombination within populations, including an overall deficiency of heterozygosity, suggesting the importance of parasexuality and/or mitotic recombination in <i>C. albicans</i> populations. Together, these results highlight the global evolutionary dynamics and population structure of <i>C. albicans</i>.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146040468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}