Canadian journal of microbiology最新文献

Gallibacterium anatis is a Gram-negative bacterium that is a pathogen and part of the microbiome of both domestic and wild birds. It is also the cause of reproductive infections, primarily when birds are stressed. Its pathogenicity has been associated with the expression of virulence factors. The effect of epinephrine (Epi) and norepinephrine (NEpi) hormones on the composition and structure of G. anatis biofilms is evaluated here. Catecholamines induced compaction and fragmentation of biofilms at 24 h. Biofilm amount diminishes (50%) by NEpi. At 48 h, biofilm fragments are immersed in exopolymer material, and the control biofilm shows a high quantity of filamentous cells, not observed with hormones. Enzymatic digestion of biofilm polymers showed increased protein levels in the presence of Epi at 24 or 48 h and NEpi at 24 or 72 h. Epi increased carbohydrate quantity, but NEpi diminished, and DNA quantities diminished at 48 h by Epi. Epi diminishes the expression of proteins in the 70-200 kDa range but increases the expression of secreted proteins. NEpi induces proteolytic activity in the range of 20-110 kDa. A 55 kDa protease was induced at 72 h by both hormones. Gallibacterium anatis biofilm changes could be significant in its dispersion and pathogenesis.

Certain Shewanella spp. cause spoilage of seafood. However, Shewanella from fish production facilities in Canada have not yet been characterized. In our study, we first isolated Shewanella oncorhynchi 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 S. oncorhynchi S-1. Rainbow trout filets inoculated with FD-1 turned brown in colour compared to uninoculated. However, when we inoculated retail pink salmon (Oncorhynchus gorbuscha) with either FD-1 or S2-3, we did not observe the brown colour change. The storage time had a significant (P < 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 Shewanella from a RAS trout facility in Alberta, Canada.

Although Citrus aurantium 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 C. aurantium, 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. Fusarium, Alternaria, Mortierella, Plectosphaerella, Cladosporium, Colletotrichum, Trichomerium, Botryotrichum, and Aspergillus were the dominant genera. The endemic and dominant genera of endophytic fungi in C. aurantium exhibited plant compartment specificity. The assembly of endophytic fungal communities was dominated by homogeneous selection of deterministic processes. The endophytic fungal genera of C. aurantium predominantly exhibited positive interactions (with a proportion > 99%). The dominant functions of endophytic fungi in C. aurantium were pathotroph and saprotroph. The composition (niche: R² = 0.09, P = 0.001; site: R² = 0.06, P = 0.021) and functional components (niche: R² = 0.117, P = 0.002; site: R² = 0.122, P = 0.006) exhibited significant plant compartment and region specificity. The results of this study reveal the characteristics of the endophytic fungal community of C. aurantium, and provide a theoretical reference for the further development and utilization of endophytic fungal resources.

Listeria costaricensis 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 L. costaricensis cannot invade HeLa cells despite displaying a cell adhesion capacity comparable to that of Listeria monocytogenes and Listeria innocua 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 L. monocytogenes strains. Finally, using the VFanalyzer platform we identified on the L. costaricensis genome 28 virulence-associated gene sequences related to regulatory and structural functions, adherence, and an incomplete invasion gene group compared to L. monocytogenes strains. Collectively, these findings phenotypically support the previously proposed non-pathogenic nature of L. costaricensis, while also revealing a level of persistence comparable to other L. monocytogenes isolates.

There is a great divide between the microbes active in natural environments and the organisms that may be grown in a laboratory setting. In this work we set out to cultivate representatives of the marine myxobacterial clade, a highly diverse, largely uncultured group of Gram-negative bacteria believed to have extensive biosynthetic potential. Sediment samples were collected from the St. Lawrence Estuary and Gulf and the presence of active marine myxobacteria was established through qPCR analysis of 16S rRNA gene and transcript abundances. In the expectation that the marine myxobacteria would exhibit predatory behaviour like their terrestrial counterparts, the sediment samples were then streaked on agar plates that contained common marine bacteria as the sole carbon source. Unexpectedly, in place of myxobacteria we isolated Pseudomonas, Bacillus, and Stenotropomonas spp., among others, revealing a generalized ability for these strains to break down living organic matter and suggesting that "bait" bacteria may be an effective approach for the cultivation of novel marine saprophytes.

We reported phage cocktails of AHP24 (T1), wV7 (T4), AKFV33 (T5), and AHP24S (rV5) had superior efficacy against STEC O157:H7 strains in broth culture and beef matrices, but it is unknown if they can lyse the pathogens in the context of intestinal epithelial cells, which may reduce Shiga toxin-producing Escherichia coli (STEC) attachment, an initial step for STEC invasion. The objective of this study was to compare efficacy of lytic phages T1, T4, T5, and rV5 as individuals or cocktails in preventing STEC attachment to human intestinal epithelial cells. Two intestinal epithelial cell lines, Caco2 and T84, that are susceptible to STEC attachment were used. There were ∼2-3 log₁₀ colony forming units/mL reductions (P < 0.0001) in STEC attachment when these epithelial cells were exposed to individual or cocktails of phages 1 h before inoculation. The phage cocktail (T5 + T1 + rV5 + T4) significantly reduced STEC attachment onto T84 cells when compared to individual phage treatments T4 and T1 (P < 0.0001). Notably, applying three- (excluding T5) or four-phage cocktails concurrent with STEC inoculation did not significantly different from phage pre-exposure. Phages may be a viable approach for preventing and treating STEC infection in human.

The chicken intestine presents a complex environment for microbial survival due to high interbacterial competition, high bile salt concentrations, a low pH, and microaerophilic conditions. While most probiotics contain members of the Bacillota phylum, members of the Pseudomonadota phylum are known to be more important in competitive exclusion-which may be an important consideration in the formulation of future probiotics. Little is known about commensal Pseudomonadota in healthy chickens, or what benefits members of this phylum may offer the host; most studies on Pseudomonadota focus on aspects of opportunistic pathogenesis and dysbiosis. In this study, we use an in silico approach to evaluate the pathogenic potential, competition strategies, and potential host benefits of Pseudomonadota isolates from healthy chickens. We analyzed the draft genomes of 29 representative isolates of Pseudomonadota using Bagle4, AntiSMash, SeCreT6, KEGG mapper, and Virsorter2 to identify key interbacterial competition strategies including secondary metabolite biosynthesis, secretion systems, quorum sensing, and prophages. Our results revealed that each isolate exhibits distinct interbacterial competitive strategies, often independent of their taxonomic affiliation. Including Pseudomonadota in future poultry probiotics may be critical to improving colonization resistance in industrially raised poultry.

Antimicrobial resistance (AMR) poses a significant threat to global health, demanding a collaborative and multi-sectoral approach to mitigate its impact. The Canadian Genomics Research and Development Initiative for Antimicrobial Resistance (GRDI-AMR) project exemplifies this approach by uniting a diverse team of experts from various Canadian science-based departments and agencies (SBDAs). This highly effective and collaborative team leverages the existing expertise within SBDAs, fostering innovation and driving advancements in AMR research. By integrating genomics and One Health principles, GRDI-AMR is generating critical knowledge and developing impactful solutions to combat AMR in Canada and beyond. This special issue provides a glimpse into the impactful outcomes generated by this collaborative network.

During highly pathogenic avian influenza (HPAI) outbreaks, the United States Department of Agriculture response requires infected egg production premises to discard on-site poultry products, including eggs that have been processed and stored prior to infection of the site. The disposal of these eggs contributes to global food insecurity through market disruptions, industry revenue loss, and federal indemnity paid. Further, rural farming communities are economically destabilized and farmer health and well-being challenged. To support continuity of business movement decisions during HPAI outbreaks, the Secure Poultry Supply team at the University of Minnesota along with an egg sector stakeholder workgroup has been examining the risk of moving to market processed, segregated, and stored eggs from an infected premises that were laid by uninfected flocks (i.e., a group of egg-laying hens kept in one house/barn during their entire lay cycle). Three important criteria for achieving both acceptable risk and confidence for movement were identified: identification and removal of potentially contaminated eggs from the cooler; protection of cooler eggs from recontamination; and science-assessed egg truck disinfection protocols for exiting an infected premises. The science behind biosecurity and biocontainment practices and risk determination for moving eggs off infected premises are discussed. Confidence in movements determined to be low risk may provide a means for farm and food-protein sustainability.