Canadian journal of microbiology最新文献

During the COVID-19 pandemic educators rapidly pivoted their instructional approaches. While this period of disruption is behind us, we are left with a legacy of experiences that can continue to benefit learners. Open educational resources improve accessibility in the classroom, and for learners globally without access to well-resourced institutional libraries. In the 2023-24 academic year, lecture videos for Veterinary Bacteriology and Mycology (a 3-credit, 2nd year DVM course at the University of Saskatchewan) were published on YouTube. Two student cohorts were surveyed about their use of the videos, and YouTube analytics was used to describe how videos were accessed globally. Students generally favoured these prerecorded videos, citing improved video quality (24%) and shorter duration (36%) compared to other courses where in-person lectures were filmed. 73% of students reported that having these videos on YouTube improved accessibility. From August 2023 through December 2024 the YouTube channel received >230,000 views from 86 countries. Approximately 6% of views originated in Canada while 62% were from low- and middle-income countries. This exercise was a positive experience yielding an easy to access repository of content to share with learners locally and globally. Other instructors are encouraged to seek out opportunities for the creation of open resources. Future studies should assess the impacts of online video sharing platforms on student learning.

Candida albicans 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 C. albicans 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 C. albicans populations. Together, these results highlight the global evolutionary dynamics and population structure of C. albicans.

High Pathogenicity Avian Influenza (HPAI) of H5 subtype was detected year-round for the first time in Europe in 2022 and contributed to the largest European HPAI epizootic. The switch H5N8 to H5N1 virus subtypes heralded a substantial increase in cases in wild and domestic birds. The impact on domestic poultry production was substantial with 120 million birds dying or being culled to control the disease. This was attributed to an expansion in the host range of wild birds affected, with infection of orders of birds not previously described as susceptible. The consequence of transmission events into naive wild bird populations was often large-scale mortality, particularly in seabirds 2022-2023. Relatively high infection pressure provided opportunity for exposure and spillover to wild mammals principally the order Carnivora, exposed through predatory or scavenging behaviour. Other sporadic infections involved farmed fur animals and a single detection in a sheep in England, but no evidence of infection in other livestock species including dairy cattle. Human infections were rare and asymptomatic, associated with close contact with infected domestic birds. The epizootic was sustained by continuing evolution in the virus principally through genetic reassortment with selection and fixation of genotypes of high fitness in the avian population.

Extracellular vesicles (EVs) are small, lipid bi-layered structures released from cell throughout the body. EVs are highly important to diverse biological processes, including cellular maintenance and homeostasis and response to infection, with potential to serve as diagnostic hallmarks of infection. Despite 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 infection with the bacterial pathogen, Klebsiella pneumoniae. 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 versus infected samples) clustering based on infection state was observed and significantly elevated fibrinogen production were reported upon infection. Conversely, assessment of the infection-exclusive EV proteome confirmed Gene Ontology Cellular Compartment classification 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 K. pneumoniae within a murine model of infection and proposes protein-level signatures indicative of bacterial infection.

Highly pathogenic avian influenza clade 2.3.4.4b H5Nx viruses (HPAIVs) have caused significant mortality in wild birds. We investigated active avian influenza virus (AIV) infections and assessed seroprevalence based on general nucleoprotein-specific and H5-specific antibodies, in seabirds in Atlantic Canada during 2022-2023. Results were compared to seroprevalence data from 2011-2016 to evaluate changes in infection rates following the incursion of HPAIV. We sampled 1073 wild live birds belonging to 14 species. Active H5Nx infections were detected only in 2022, with the highest prevalence in Common Murres (64%), followed by Black-legged Kittiwakes (13%). Differences in seroprevalence were observed between years and species, with both Common Murres and Atlantic Puffins exhibiting higher rates after HPAIV incursion, particularly for anti-H5-specific antibodies. Seroprevalence also differed between locations, and age-related differences in exposure were observed with juvenile birds having much lower seroprevalence than adult birds, particularly among gulls. Despite no active infections being detected in 2023, high seroprevalence across species suggests persisting immunity and/or recent virus circulation. These findings underscore the importance of serological monitoring in tracking AIV dynamics, as antibody detection provides critical insights into past HPAIV exposure even when active infection rates are low.

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 (db-RDA, R² = 0.20, p < 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 ρ = 0.6, P < 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.

Unprecedented seabird mass mortality events (MMEs) were reported in multiple European countries in 2022 and 2023. These events were attributed to Clade 2.3.4.4b H5N1 high pathogenicity avian influenza viruses (HPAIVs). In Denmark, populations of Sandwich Terns (Thalasseus sandvicensis) and Black-headed Gulls (Chroicocephalus ridibundus) were significantly impacted. Sandwich Tern mortality occurred primarily between May and June of 2022 and was caused by the HPAIV genotype EA-AB. From 2022 to 2023, Danish Sandwich Tern populations decreased by 36%. Sandwich Terns commonly nest within Black-headed Gull colonies, allowing for direct contact between the species. Despite their proximity, in 2022, neither adults nor chicks of Black-headed Gulls exhibited morbidity associated with HPAIV. During the autumn of 2022 and the winter 2022/23 a novel clade 2.3.4.4b H5N1 HPAIV, genotype EA-BB, emerged in Black-headed Gulls. The new genotype caused the death of at least 3000 adult Black-headed Gulls in Denmark (i.e. >1.8% of the Danish breeding population) in the spring of 2023. Notably, in 2023 Sandwich Tern chicks, but not adults, in contact with black-headed gulls were affected by mass mortality. These observations suggest that adult Terns in 2023 were less susceptible to HPAIV infection, mitigating the impact of MMEs.

Tomato (Solanum lycopersicum) is one of the most widely cultivated vegetables worldwide, yet its productivity is severely constrained by Fusarium wilt caused by FOL. The pathogen invades the root system and vascular tissues, leading to systemic wilting, plant collapse, and significant yield losses. Although chemical fungicides have been extensively used for management, their long-term effectiveness is declining due to the emergence of fungicide-resistant strains and the associated environmental and health hazards. This growing challenge underscores the urgent need for sustainable alternatives. In this review, we critically synthesize recent advances in the biological control of FOL, focusing on antagonistic fungi, beneficial bacteria, and the role of organic amendments in creating suppressive soils. Unlike earlier reviews that address these components separately, we emphasize their integration within holistic disease management frameworks. We also highlight promising directions, including microbial consortia, molecular insights into pathogen-antagonist interactions, and the potential of combining biological control with precision agriculture tools. Collectively, these strategies offer a sustainable pathway for mitigating Fusarium wilt and ensuring resilient tomato production systems.

Hyriopsis cumingii is an important economic freshwater shellfish in China and there is a need to understand changes in the microbial community structure resulting in multidimensional quality degradation when the fish is stored at different temperatures. This study integrated 16S rRNA full-length sequencing with multidimensional quality indicators to investigate the temperature-regulated bacterial community shifts and quality deterioration mechanisms in stored H. cumingii meat. The results showed that bacterial richness (Chao1 index) decreased progressively with both refrigerated (4 °C) and room-temperature (25 °C) storage. Community composition underwent significant restructuring, with Bacteroidota decreasing at 25 °C while Bacillota increased compared to 4 °C storage. Additionally, the refrigerated group showed enrichment of Delftia turuhatensis and Chryseobacterium indologenes compared to the room-temperature storage group. Temperature significantly restructured bacterial communities, with notably higher pathogenic bacteria under refrigeration and spoilage bacteria dominance at room temperature. Metagenomic functional profiling revealed temperature-driven metabolic pathway divergence, indicating distinct spoilage mechanism. Predictable quality changes in H. cumingii correlated with temperature-imposed microbial composition.

Atherosclerotic cardiovascular disease (ASCVD) is a global health concern, leading to higher rates of morbidity and mortality. Gut microbial dysbiosis significantly contributes to obesity related ASCVD. However, the interrelation of gut microbiome in driving obesity or overweight mediated ASCVD has not been sufficiently investigated. To unravel this complex interplay, we have compared the gut microbial shotgun metagenome data of ASCVD subjects across normal BMI (Body Mass Index) and overweight/obese (OW/OB) BMI categories. We identified a distinct gut microbial composition and function in normal and OW/OB ASCVD subjects. Using gut microbial abundance, a machine learning model was built to predict ASCVD in the normal and OW/OB samples. The gut microbiome-based signature for ASCVD discrimination was achieved with an AUC of 0.87 and 0.83 for distinguishing control and ASCVD in normal and OW/OB BMI groups, respectively. In addition, we have also identified that Pseudoflavonifractor capillosus could act as a prognostic organism in identifying OW/OB associated ASCVD. Therefore, an appropriate diet could modify the ASCVD contributing gut microbiome, hence minimizing the risk of ASCVD in OW/OB individuals.