Canadian journal of microbiology最新文献

The Cryptococcus neoformans and Cryptococcus gattii species complexes are the etiological agents of cryptococcosis, a disease responsible for 181 000 deaths annually worldwide due to late diagnosis and limited treatment options. Studies focusing on the identification of new substances with antifungal activity, such as essential oils (EOs), are urgently needed. While the antifungal effects of EO have already been suggested, their mechanism of action at the molecular level still requires evaluation. In this work, we assessed the molecular changes induced by the exposure of Cryptococus neoformans (H99) and Cryptococcus deuterogatti (R265) to lavender essential oil (LEO) using a morphological and proteomics approach. The identified proteins were categorized by Gene Ontology according to biological processes and molecular functions, and Kyoto Encyclopedia of Genes and Genomes pathway analysis was also conducted. Our findings indicate that LEO creates a stressful environment in both strains; however, the response to this stimulus differs between the two species. In C. neoformans, changes were observed in energy metabolism and pathways related to alternative sources of energy and oxidative stress response. In C. deuterogatti, changes were identified in pathways related to cellular architecture, implying that the cell underwent morphological changes such as membrane and cell wall stiffening.

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.

The objective of this study was to compare chlorhexidine digluconate and other antibiotics susceptibility of four species of theAcinetobacter baumannii complex, and further investigate the chlorhexidine digluconate (CHG) tolerance mechanisms and molecular epidemic characteristics. Of 889 A. baumannii complex isolates, A. baumannii, A. nosocomialis, A. pittii, and A. seifertii accounted for 84.2%, 10.9%, 3.4%, and 1.5%. Acinetobacter baumannii was generally resistant to all tested antibiotics, while other three species were commonly more susceptible; 92.1% (313/340) CHG-tolerant A. baumannii, 19.6% (19/97) CHG-tolerant A. nosocomialis, 3.3% (1/30) CHG-tolerant A. pittii, and 15.4% (2/13) CHG-tolerant A. seifertii were identified. Furthermore, compared to A. baumannii ATCC 19606, upregulated expression was found in qacE_Δ1, fabI, and efflux pump encoding genes in CHG-tolerant A. baumannii, but the expression level of oprD was reduced. Additionally, only the expression level of fabI was increased in the CHG-tolerant A. nosocomialis, and the expression level of adeG was increased in the CHG-tolerant A. pittii and A. seifertii. Furthermore, CHG-tolerant A. baumannii may have a relatively high clonal correlation, the predominant sequence type of which was ST208 (90%, 36/40). It is rather necessary to identify specific species members among the A. baumannii complex for clinical treatment options and antibiotics resistance monitoring.

Klebsiella pneumoniae is a ubiquitous opportunistic pathogen of the family Enterobacteriaceae. K. pneumoniae is a member of the ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), a group of bacteria that cause nosocomial infections and are able to resist killing by commonly relied upon antimicrobial agents. The acquisition of antimicrobial resistance (AMR) genes is increasing among community and clinical isolates of K. pneumoniae, making K. pneumoniae a rising threat to human health. In addition to the increase in AMR, K. pneumoniae is also thought to disseminate AMR genes to other bacterial species. In this review, the known mechanisms of K. pneumoniae AMR will be described and the current state of AMR K. pneumoniae within Canada will be discussed, including the impact of the coronavirus disease-2019 pandemic, current perspectives, and outlook for the future.

Plant growth promotion by Pseudomonas sp. 31-12 incorporated into a lettuce seed pelleting matrix was studied. We examined (1) the effect of five rhizosphere derived bacterial strains on green oak lettuce (Lactuca sativa L.) seed germination, root and shoot growth, as a strain selection step for seed coating and seed pelletizing studies, (2) population stability of Pseudomonas sp. 31-12 incorporated into a pelleting matrix on lettuce seed stored three months at 4 °C, and (3) lettuce growth promotion in the laboratory and greenhouse by Pseudomonas sp. 31-12 coated and pelletized seed. A spontaneous streptomycin mutant of Pseudomonas sp. 31-12 (str) was used to determine population size on seed and roots of 15- and 30-day-old lettuce. The population of Pseudomonas sp. 31-12str on coated and pelleted seed decreased from 10⁴ cfu/seed to 10³ cfu/seed after 3 months storage at 4 °C. However, the population exceeded 10⁴ cfu/g root dry mass and 10⁵/g root dry mass after 15 days and 30 days in the greenhouse. Leaf fresh mass was significantly increased (P ≤ 0.05) with Pseudomonas sp. 31-12 seed treatment as compared to noninoculated seed. In conclusion, pelletized lettuce seed with Pseudomonas sp. 31-12 promoted growth and yield in the greenhouse.

Frankia represent a unique group of filamentous, sporangia-forming bacteria, renowned for their exceptional capacity to establish symbiotic partnerships with actinorhizal plants. The objective of this paper is to offer quantitative insights into the current state of frankia research and its future potential. A comprehensive bibliometric analysis covering the years 2000-2022 was conducted using Scopus and SciVal. A steady increase in both annual publication and international collaboration has been observed, particularly since 2013. Research performance metrics for the last 5 years (2018-2022) indicate China and India as leaders with high Field-Weighted Citation Impact scores. This analysis highlighted prominent authors, research groups, and the evolving research landscape, suggesting an increasing focus on molecular and genomic aspects. The genomic era has transformed our understanding of frankia biology, highlighting their significance in diverse ecological and agricultural contexts. This study comprehensively maps the evolving landscape of frankia research, emphasizing key milestones that have catalysed international interest in frankia-actinorhizal research, expanding our perception of frankia's capabilities beyond its traditional symbiotic role. As research in this field progresses, a deeper comprehension of frankia-plant interactions, symbiotic signalling, and the intricacies of metabolic pathways holds the promise of revealing innovative techniques for optimizing nitrogen fixation and broadening the spectrum of host plants.

The principal methods to maintain soil fertility in Sahel soils are largely allowing fields to go fallow and manure addition. These methods are not currently sufficient to improve soil fertility. To promote biological amendments, we aimed to understand the plant-growth promoting traits of various soil microbial isolates. The soils collected in different areas in Senegal exhibited a similar eDNA profile of bacteria; the dominant microbes were Firmicutes, followed by Proteobacteria and Actinobacteria. Of 17 isolates identified and tested, the vast majority solubilized rock phosphate and a large number grew on culture medium containing 6% salt, but very few degraded starches or hydrolysed carboxymethyl cellulose or produced siderophores. Upon single inoculation, Peribacillus asahii RC16 and Dietzia cinnamea 55 significantly increased pearl millet growth and yield parameters. For cowpea, plant shoot length was significantly increased by Pseudarthrobacter phenanthrenivorans MKAG7 co-inoculated with Bradyrhizobium elkanii 20TpCR5, and nearly all rhizobacteria tested significantly improved cowpea dry weight and pod weight. Additionally, the double inoculation of Dietzia cinnamea 55 and MKAG7 significantly increased shoot length, dry weight, and seed head weight of pearl millet. These isolates are promising inoculants because they are ecologically-friendly, cost-effective, sustainable, and have fewer negative effects on the soil and its inhabitants.

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.