Canadian journal of microbiology最新文献

Many arthropods, including economically important pests of stored grains, host intracellular bacterial symbionts. These symbionts can have diverse impacts on host morphology, stress tolerance, and reproductive success. The ability to rapidly determine the infection status of host insects and the identity of intracellular symbionts, if present, is vital to understanding the biology and ecology of these organisms. We used a microbiome profiling method based on amplicon sequencing to rapidly screen 35 captive insect colonies. This method effectively revealed single and mixed infections by intracellular bacterial symbionts, as well as the presence or absence of a dominant symbiont, when that was the case. Because no a priori decisions are required about probable host-symbiont pairing, this method is able to quickly identify novel associations. This work highlights the frequency of endosymbionts, indicates some unexpected pairings that should be investigated further, such as dominant bacterial taxa that are not among the canonical genera of endosymbionts, and reveals different colonies of the same host insect species that differ in the presence and identity of endosymbiotic bacteria.

Vibrio parahaemolyticus produces a key virulent factor known as thermostable direct hemolysin (TDH). TDH exhibits diverse biological activities, including hemolytic activity. The β-type hemolysis observed on Wagatsuma agar due to TDH is recognized as the Kanagawa phenomenon (KP). The tdh2 gene is primarily responsible for TDH production and the associated KP. AcsS was originally identified as an activator of swimming and swarming motility in V. parahaemolyticus. However, its potential roles in other cellular pathways remain unclear. In this study, we investigated the regulatory effects of AcsS on the hemolytic activity and tdh2 expression in V. parahaemolyticus using phenotypic tests for KP, quantitative real-time polymerase chain reaction, LacZ fusion, and electrophoretic mobility shift assays. The data showed that V. parahaemolyticus hemolytic activity and tdh2 transcription were under the negative control of AcsS. Additionally, in-vitro binding assays revealed that His-AcsS could not bind to the regulatory DNA region of tdh2. However, overexpression of AcsS in an Escherichia coli strain suppressed the expression of tdh2. Collectively, these results suggested that AcsS suppresses the hemolytic activity of V. parahaemolyticus through the downregulation of tdh2 transcription. The data enhanced our understanding of the regulatory networks governing tdh2 expression and the roles of AcsS in this bacterium.

Rabies is a zoonotic infectious disease that targets the nervous system of human and animals and has about 100% fatality rate without treatment. Rabies virus is a bullet-like viral particle composed of five structural proteins, including nucleoprotein (N), phosphorylated protein (P), matrix protein (M), glycoprotein (G), and large subunit (L) of RNA-dependent RNA polymerase. These multifunctional viral proteins also play critical roles in the immune escape by inhibiting specific immune responses in the host, resulting in massive replication of the virus in the nervous system and abnormal behaviors of patients such as brain dysfunction and hydrophobia, which ultimately lead to the death of patients. Herein, the role of five structural proteins of rabies virus in the viral replication and immune escape and its implication for the development of vaccines were systemically reviewed, so as to shed light on the understanding of pathogenic mechanism of rabies virus.

Less than 1% of native prairie lands remain in the United States. Located in eastern Washington, the rare habitat called Palouse prairie was largely converted to wheat monocropping. With this conversion came numerous physical, chemical, and biological changes to the soil that may ultimately contribute to reduced wheat yields. Here, we explored how wheat (Tritcum aestivum L.) seedling establishment, plant size, and heading, signifying the developmental transition to flowering, were affected by being planted in prairie soil versus agricultural soils. We then sought to understand whether the observed effects were the result of changes to the soil microbiota due to agricultural intensification. We found that prairie soil enhanced both the probability of wheat seedling survival and heading compared to agricultural soil; however, wheat growth was largely unaffected by soil source. We did not detect effects on wheat developmental transitions or phenotype when inoculated with prairie microbes compared with agricultural microbes, but we did observe general antagonistic effects of microbes on plant size, regardless of soil source. This work indicates that agricultural intensification has affected soils in a way that changes early seedling establishment and the timing of heading for wheat, but these effects may not be caused by microbes, and instead may be caused by soil nutrient conditions.

Antimicrobial resistance is an ever-increasing threat. The widespread usage of ciprofloxacin has led to the manifestation of resistance due to chromosomal mutations or the acquisition of plasmid-mediated quinolone resistance (PMQR) traits. Some particular PMQR traits, qnr genes, have been identified globally in clinical and environmental isolates. This study aimed to determine the prevalence of ciprofloxacin-resistant bacteria in aquatic environments in southern Ontario and investigate the extent of dissemination of ciprofloxacin resistance traits among the bacterial communities. We surveyed the prevalence of plasmid encoding qnr genes using a multiplex PCR assay of associated PMQR genes, qnrA, qnrB, and qnrS, on 202 isolates. Despite the absence of significant impacts on minimum inhibitory concentration levels, the presence of qnr genes correlates with heightened resistance to quinolones and nalidixic acid in some isolates. Taxonomic analysis highlights distinct differences in the composition and diversity of ciprofloxacin-sensitive (CipS) and ciprofloxacin-resistant (CipR) populations, with Proteobacteria dominating both groups. Importantly, CipR populations exhibit lower genetic diversity but higher prevalence of multiple antibiotic resistances, suggesting co-selection mechanisms. Co-occurrence analysis highlights significant associations between ciprofloxacin resistance and other antibiotic resistances, implicating complex genetic linkages. The results of our study signified the critical role of environmental monitoring in public health.

Mine environments in boreal and sub-boreal zones are expected to experience extreme weather events, increases in temperature, and shifts in precipitation patterns. Climate change impacts on geochemical stability of tailings contaminants and reclamation structures have been identified as important climate-related challenges to Canadian mining sector. Adapting current reclamation strategies for climate change will improve long-term efficiency and viability of mine tailings remediation/restoration strategies under a changing climate. Accordingly, mesocosm experiments were conducted to investigate associations of climate-driven shifts in microbial communities and functions with changes in the geochemistry of organic covers and underlying tailings. Our results show that warming appears to significantly reduce C:N of organic cover and promote infiltration of nitrogen into deeper, unoxidized strata of underlying tailings. We also observed an increase in the abundance of some nitrate reducers and sulfide oxidizers in microbial communities in underlying tailings. These results raise the concern that warming might trigger oxidation of sulfide minerals (linked to nitrate reduction) in deeper unoxidized strata where the oxygen has been eliminated. Therefore, it would be necessary to have monitoring programs to track functionality of covers in response to climate change conditions. These findings have implications for development of climate resilient mine tailings remediation/restoration strategies.

Lake Guamuez is the second largest lake in Colombia and economically supports hundreds of families in the area. The main activities carried out in the region have focused on tourism, agriculture, livestock, and rainbow trout production; however, these activities have been associated with contamination of the lake. This research aimed to evaluate the water quality of Lake Guamuez using somatic coliphages (SCs) as bioindicators. For this purpose, periodic sampling was carried out for 6 months at nine strategic points of the lake. For the detection of SCs, the method described in 9211 D of the Standard Methods for the Examination of Water and Wastewater was used. The genomic variability and presence of virulence genes in the isolated SCs were determined. Water contamination in the lake is evident, and the SCs titer is greater in areas with a high flow of anthropogenic activities. An important degree of genetic diversity and a high prevalence of virulence genes could be observed among the SCs analyzed. The results when compared with guidelines and water quality standards from various countries showed concentrations of SCs higher than those allowed. The high prevalence of gastrointestinal diseases in the region suggests a link to water contamination.

Highlights: S. Heidelberg survived up to 21 days in PWS which is often used as broiler bedding. S. Heidelberg abundance and survival was correlated with the water activity of PWS. S. Heidelberg strains that carried higher copy numbers of small Col plasmids were the dominant strains isolated from PWS at later time points. S. Heidelberg strains harboring transmissible plasmid carrying AmpC-like beta-lactamase gene persisted longer in PWS without antibiotic pressures for AMR.

Highlights: Cannabidiol (CBD) decreases the growth of C. albicans. CBD inhibits the yeast-to-hyphae transition. CBD reduces biofilm formation by C. albicans. CBD induces C. albicans death through necrosis.

Aspergillus fumigatus is a globally distributed mold and a major cause of opportunistic infections in humans. Because most infections are from environmental exposure, it is critical to understand environmental populations of A. fumigatus. Soil is a major ecological niche for A. fumigatus. Here, we analyzed 748 soil isolates from 21 locations in six provinces and one territory in Canada. All isolates were genotyped using nine microsatellite markers. Due to small sample size and/or close proximities for some local samples, these isolates were grouped into 16 local geographic and ecological populations. Our results indicated high allelic and genotypic diversities within most local and provincial populations. Interestingly, low but statistically significant genetic differentiations were found among geographic populations within Canada, with relatively similar proportions of strains and genotypes belonging to two large genetic clusters. In Hamilton, Ontario, and Vancouver, BC, where two and three ecological populations were analyzed, respectively, we found limited genetic difference among them. Most local and provincial populations showed evidence of both clonality and recombination, with no population showing random recombination. Of the 748 soil isolates analyzed here, two were resistant to triazole antifungals. We discuss the implications of our results to the evolution and epidemiology of A. fumigatus.