This study, conducted between 2018 and 2024, expands upon prior research through a culture-based investigation of the spatiotemporal prevalence, distribution, and diversity of Acinetobacter species across nine sites in an agriculturally-dominated watershed in eastern Ontario, Canada. Spatial analyses revealed, compared to medium to large stream order sites and forested reference site, agricultural drainage ditches consistently displayed higher Acinetobacter prevalence, cell concentrations, and diversity, likely due to direct proximity to livestock farms. Summer exhibited the highest Acinetobacter abundance and diversity, a pattern potentially linked to elevated temperatures, water stagnation, and seasonal runoff. Species-level identification revealed the widespread and persistent detection of several human health-associated species, including A. baumannii and A. pittii. The association of Acinetobacter species with upstream urban and agricultural land uses suggests that anthropogenically influenced waters may serve as critical sources for the environmental dissemination of pathogenic Acinetobacter and antimicrobial resistance genes. Furthermore, environmental Acinetobacter species, such as A. calcoaceticus, A. guillouiae, A. johnsonii, and A. soli, may play underappreciated roles in gene transfer and infection risk. This first in-depth analysis of Acinetobacter species within an agricultural aquatic ecosystem, offering a foundation for future research into environmental reservoirs of potential human pathogens and the spatiotemporal factors shaping microbial populations.

Salmonella enterica is an important zoonotic pathogen affecting animal and human health. Using a One Health approach, we conducted a comparative genomic analysis of S. enterica recovered within a restricted peri-urban region in Western Canada consisting of six dairy farms, an organic poultry farm, surrounding environments, and municipal wastewater. Overall, Salmonella prevalence was low, with 34 of 1,004 samples (3.4%) testing positive and representing 11 serovars. Antimicrobial resistance was limited: all isolates were susceptible to 12 of 14 antimicrobials tested, with resistance detected only to streptomycin (35%) and tetracycline (12%). Although all isolates carried the cryptic aminoglycoside resistance gene aac(6')-Iaa and 65% harboured the parC T57S mutation, neither determinant was associated with phenotypic resistance. Serovar Kentucky was the most widely distributed, occurring in dairy, poultry, and environmental samples. Plasmid profiles indicated genomic linkages among isolates from dairy farms, poultry, and the environment. Phylogenomic analyses revealed genetic similarities across animal and environmental sectors, while comparison with publicly available S. enterica ser.Enteritidis genomes identified a potential linkages between poultry and dairy production systems. These findings highlight the low prevalence of Salmonella in the study region and the value of One Health surveillance for identifying reservoirs, transmission pathways, and opportunities to strengthen biosecurity.

DNA capture-based sequencing by hybridization probe enrichment (CapSeq) affords high-throughput and targeted gene-to-organism detection. Despite the specificity designed into CapSeq platforms, untargeted DNA represents additional genes and organisms of interest. To this end, de novo metagenome assemblies of CapSeq datasets present opportunities for discovery. We report an example here. CapSeq of samples that originated from cattle suffering from septic arthritis (SA) resulted in detection and assembly of two ungulate tetraparvovirus 1 genomes. These coincidental detections and assemblies were obtained from a platform designed to characterize bacterial, not viral, pathogens. Access to a sample matched shotgun metagenomic dataset corroborated the result. Importantly, SA is a significant source of lameness in beef cattle that lacks effective and approved treatments, and the list of aetiological agents is incomplete. This metagenomic observation calls attention to the possible implication of viral contributors to bovine SA, which is treated as a bacterial disease. The results exemplify the potential application of unbiased CapSeq data mining to support clinical discoveries.

Soil oomycetes contain some of the most devastating plant pathogens, and are widespread within the soil microbiome, yet how individual plant species structure oomycete communities in natural soils, and whether any such structuring is consistent across space, remains poorly resolved. Because host-specific pathogen accumulation is a central prediction of plant-soil feedback theory but is rarely tested outside greenhouse conditions, we focused on whether the host-specific fraction of these communities is preferentially pathogenic. Using oomycete-specific internal transcribed spacer amplicons, we sequenced rhizosphere-associated and paired bulk soils from four grassland species across 25 sites on the Canadian Prairies spanning more than 200 000 km[2], totalling 1800 samples. Each host supported a distinctive core of taxa, with two species more likely to host pathogenic taxa unique to their rhizosphere. This enrichment was decoupled from richness of oomycete taxa in the rhizosphere, indicating selective accumulation rather than a by-product of resource-rich environments. Community composition also differed among hosts after accounting for site level edaphic variation. Host plant identity therefore leaves a detectable, spatially repeatable imprint on soil oomycete communities, one expressed most strongly through the selective accumulation of pathogenic taxa.

Exudative epidermitis (EE) in piglets, caused by the bacterium Staphylococcus hyicus, remains a major concern for the swine industry, particularly due to antimicrobial resistance. Bacteriophages represent a promising alternative treatment. This study aimed to isolate and characterize phages infecting S. hyicus from EE-affected swine farm environments in Quebec. Four novel phages (BQE1, BQE4, BQE7, BQL4) were isolated from water and manure samples. All produced clear plaques (<1 mm) and reached titers of 10[8]-10[10] PFU/mL. Electron microscopy revealed myovirus morphology. Their genomes (115.4-134.5 kb) are closely related to the already described Twort phage but distinct from other S. hyicus phages. No virulence or antimicrobial resistance genes were detected in their genome. Host range analysis across 58 staphylococcal strains showed broad activity against S. hyicus (77%-80% susceptibility), whereas the Twort phage was largely ineffective (4%). Adsorption and growth assays indicated efficient infection, with latent periods of ∼50 min and burst sizes of 10-13 PFU/cell. Phages remained stable at 4 °C and room temperature but were less stable at 31 °C. Overall, these Twort-like phages display strong lytic activity and favorable genomic and biological characteristics, supporting their potential as targeted alternatives to antibiotics for controlling EE in swine production.

Blue light is a critical signal that triggers fruiting body initiation in mushroom-forming fungi. Pleurotus ostreatus is a cultivated model mushroom. The molecular mechanisms linking light perception to primordia formation remain poorly understood. We functionally characterized the blue light receptor gene PoWC-1, a homolog of Neurospora crassa white collar 1, during morphogenesis. Antisense-mediated silencing of PoWC-1 caused a delay in primordia formation under light/dark cycles and complete arrest at the undifferentiated mycelial stage under continuous darkness, underscoring its role in developmental progression. In darkness, PoWC-1 silencing downregulated key developmental transcription factors, hom1, hom2, Pofst3, and fst4, suggesting that PoWC-1 may contribute to developmental competence independently of light. Comparative transcriptomics revealed PoWC-1 influences a range of metabolic pathways-such as glycolysis/gluconeogenesis, the pentose phosphate pathway, and amino sugar metabolism-that may support the energetic and biosynthetic demands of fruiting initiation. In addition, PoWC-1 appears to affect upstream signaling components, including the MAPK pathway and the two-component system, along with a suite of downstream transcription factors. These findings suggest that PoWC-1 functions as a key regulator integrating blue light signals into a multi-layered network involved in metabolic reprogramming, signal transduction, and transcriptional regulation during primordia formation in P. ostreatus. Collectively, this study provides a molecular framework for understanding photomorphogenesis in edible mushrooms.

Arbuscular mycorrhizal fungi (AMF) form symbioses in terrestrial ecosystems, yet plant responses to AMF-rich soil inocula are variable and do not necessarily reflect root colonization. We investigated how plant successional strategy and AMF-rich soil inocula interact to drive plant performance and root colonization structures. In a greenhouse experiment, four early- and late-successional native grasses were grown with five trap-cultured AMF-rich whole soil inocula. We assessed responses in biomass and height, expressed as log response ratios relative to sterile controls, alongside intraradical hyphal and arbuscular colonization. Biomass responses were generally negative and depended on the interaction between inoculum treatment and successional group. Late-successional species exhibited less negative growth responses than early-successional species. The probability of detecting hyphal colonization differed among inoculum treatments, whereas arbuscular colonization depended on the interaction between inoculum and successional group. However, neither arbuscules nor hyphal colonization predicted biomass responses, showing that greater physical colonization does not necessarily translate into greater plant growth. These findings show that structural colonization alone is insufficient to predict the growth effects of AMF-rich whole soil inocula. For grassland restoration, our results highlight that evaluating soil inocula based solely on physical colonization is insufficient; successful management requires assessing their functional effects on target native grasses.

Understanding the phage resistance mechanisms in Erwinia amylovora is crucial for improving phage therapy applications targeting this plant pathogen, which is responsible for fire blight disease in apple and pear orchards. This study investigated E. amylovora phage resistance in the presence of peptidylarginine deiminase (PAD) inhibitors, which have been found in other studies to prevent the conversion of arginine to citrulline as a post-translational modification that may initiate outer membrane vesical (OMV) formation. Infection of the E. amylovora Ea6-4 strain by ϕEa21-4 phages, in the presence of either GSK199 or Cl-Amidine, demonstrated higher infection efficacy and larger phage lysis areas compared to the control infections without PAD inhibitors. Our data suggest that E. amylovora could conceivably employ OMVs as a possible passive phage resistance mechanism in addition to the previously identified regulator of capsule synthesis, the two-component RCS-based phage resistance system.

The 8th edition of the Annual Canadian Synthetic Biology Symposium (SynBio 8.0) was hosted at the University of Waterloo from June 15 to 17. It brought together around 140 attendees from across Canada, as well as international participants. Organized by the Waterloo Centre for Microbial Research (WCMR) alongside SynBio Canada, SynBio 8.0 captured both the range of the work underway and the energy running through Canada's synthetic biology community. Across the scientific program, topics moved from biomanufacturing and enzyme engineering to environmental microbiology, new tool development, and plant synthetic biology. Several keynote talks and panel discussions on practical issues were the center of the conference. Trainees learned about intellectual property, key aspects of starting companies, and how scientists can better communicate their work. This edition was marked by record-setting poster numbers, serving as a clear signal that the field is accelerating the pace in Canada. Here we gathered the main viewpoints that surfaced over the three days, offering a snapshot of a discipline that is increasingly varied, confident, and established nationwide.

The World Health Organization includes Aspergillus fumigatus on the list of fungal pathogens of critical priority for the development of new therapeutic options, due to the emergence of antifungal-resistant strains and high mortality rates. This work evaluated the antifungal activity of vanillin, o-vanillin, ethyl vanillin, and vanillin acetate against A. fumigatus. Broth microdilution assays were performed to determine the minimum inhibitory concentrations of the phenolic compounds. Moreover, the ability of vanillin and its derivatives to inhibit conidial adhesion and biofilm formation at subinhibitory concentrations was assessed. The possible mechanism of action of the compounds by molecular docking was evaluated. Finally, the therapeutic efficacy of the molecules was analyzed in an in vivo aspergillosis model. Vanillin and its derivatives exhibited antifungal effects against A. fumigatus at concentrations of 0.25-1 mmol/L; notably, o-vanillin showed higher antifungal activity (0.25 mmol/L). Furthermore, vanillin, o-vanillin, and vanillin acetate reduced conidial adhesion and biofilm formation at subinhibitory concentrations. These compounds decreased ergosterol concentration, and in silico analysis showed that phenolic compounds interact with ERG5, ERG6, and ERG11. Vanillin and o-vanillin demonstrated therapeutic efficacy against an aspergillosis model. Overall, these results highlight the antifungal activity of vanillin and o-vanillin against A. fumigatus as a potential therapeutic alternative.

Bacillus cereus emetic poisoning is mediated by cereulide, a thermostable cyclic depsipeptide encoded by the cesA/cesB operon under PlcR-PapR control. Once formed, cereulide resists heat and standard food processing, making transcriptional intervention the only viable biocontrol strategy. Lacticaseibacillus casei National Collection of Industrial Microorganisms (NCIM) 2125, Lactiplantibacillus plantarum NCIM 2083, and a three-strain consortium additionally containing Bifidobacterium bifidum NCIM 5697 were co-cultured with B. cereus NCIM 2217 in brain heart infusion broth (1:1 v/v; OD600 = 0.1; 37 °C) over 24-72 h (n = 3). Viable counts were determined by standard plate count, cereulide by LC-MS following liquid-liquid extraction, and cesA/cesB transcripts by RT-qPCR (2[-]ΔΔCT, dual housekeeping-gene normalisation). Lacticaseibacillus casei inhibited growth at 24 h only (1.97 log CFU/mL; p = 0.021). The consortia achieved 18.0% area-under-curve reduction and 81.6% cereulide suppression at 48 h (p < 0.001; Cohen's d = 29.03). A protein-mRNA paradox emerged: L. plantarum suppressed cesA by 87.9% at 48 h, yet cereulide rose 10.5% above control (p = 0.007), attributable to depsipeptide stability post-secretion. Consortium ces silencing at 24 h (cesA FC = 0.0031) preceded peak synthesis, yielding a 77.5 percentage-point synergy bonus. Effective cereulide biocontrol requires ces silencing before the synthesis window closes, a criterion met only by the consortia.

The objective of this study was to determine the presence of quaternary ammonium compound (QAC) resistance genes in Listeria spp. strains and to evaluate the effect of temperature and substrate on interspecies gene transfer. A total of 23 L. monocytogenes strains, four L. innocua and 37 Listeria spp. isolates (excluding L. grayi, L. ivanovii, L. seeligeri, and L. welshimeri) were recovered from surfaces in a frozen vegetable processing facility. The presence of the bcrABC gene was assessed by endpoint PCR. The bcrABC gene was detected in 73.91% (17/23) of L. monocytogenes isolates, in 50.00% (2/4) of L. innocua strains and was not detected in the other Listeria species (0/37). Two L. innocua strains carrying the bcrABC gene and two L. monocytogenes strains lacking it were selected for mixed culture experiments. Four co-cultures were prepared, inoculated into tryptic soy broth and spinach extract, and incubated at 4, 25, and 36 °C for 10 days. Horizontal transfer of the bcrABC gene was observed in 7.87% (17/216) of reactions in tryptic soy broth and spinach extract, with higher frequencies at 25 °C (10/216, 4.63%) and 36 °C (6/216, 2.78%) and lower frequencies at 4 °C (1/216, 0.46%). Recipient L. monocytogenes strains revealed increased resistance to QACs (500 μg/mL).

Plant growth-promoting rhizobacteria (PGPR) offer a sustainable alternative to mitigate the excessive use of synthetic agrochemicals in modern agriculture. This study focused on the isolation and molecular characterization of endophytic bacteria from jalapeño pepper (Capsicum annuum L.) to evaluate their multi-functional PGPR traits and antagonistic activity against phytopathogenic fungi. Phylogenetic analysis identified several genera, including Stenotrophomonas, Pseudomonas, Paenibacillus, Klebsiella, Aeromonas, and Enterobacter. Among these, Klebsiella IR6 and Enterobacter IR9 significantly enhanced vegetative vigor under greenhouse conditions compared to the untreated control. These isolates demonstrated robust phosphate solubilization, siderophore production, and in vitro antagonism against Fusarium oxysporum (15%-34% growth inhibition). Furthermore, endophytic colonization of the root tissues by Klebsiella IR6 was successfully validated via confocal scanning microscopy using green fluorescent protein-tagged cells transformed with the pAD4325 plasmid. These findings suggest that Enterobacter and Klebsiella isolates are promising biotechnological tools for optimizing horticultural yields, while reducing chemical dependence. Nevertheless, further field evaluations across diverse jalapeño hybrids are essential to validate the consistency and stability of both as reliable bio-inoculants for sustainable agriculture.

Foodborne botulism is a severe neuroparalytic disease caused by ingestion of foods containing botulinum neurotoxins, produced by Clostridium botulinum. In 2024, a 74-year-old woman from Newfoundland and Labrador with complete bilateral flaccid paralysis and respiratory distress was hospitalized and required intubation. From the broader differential diagnosis list, botulism was favoured prior to laboratory confirmation. Serum and feces samples initially tested negative for botulinum neurotoxins by mouse bioassay, yet viable C. botulinum type A was recovered from the feces. Food history investigation included some diced garlic in a repurposed coffee container that tested negative for botulinum neurotoxins by mouse bioassay, but viable C. botulinum type A was recovered from the sample. Both the fecal and garlic enrichment cultures were positive for bont/A and bont/B genes by real-time PCR. Whole genome sequencing revealed that both fecal and garlic isolates were highly similar with conserved gene synteny, including an intact bont/A1 gene and a disrupted (silent) bont/B5 gene encoded on the chromosome. This single-case foodborne botulism outbreak from Newfoundland and Labrador in 2024 was caused by C. botulinum type A1(B5) in diced garlic.