Project description:Pseudomonas aeruginosa ExoU, a type III secretory toxin and major virulence factor with patatin-like phospholipase activity, is responsible for acute lung injury and sepsis in immunocompromised patients. Through use of a recently updated bacterial genome database, protein sequences predicted to be homologous to Ps. aeruginosa ExoU were identified in 17 other Pseudomonas species (Ps. fluorescens, Ps. lundensis, Ps. weihenstephanensis, Ps. marginalis, Ps. rhodesiae, Ps. synxantha, Ps. libanensis, Ps. extremaustralis, Ps. veronii, Ps. simiae, Ps. trivialis, Ps. tolaasii, Ps. orientalis, Ps. taetrolens, Ps. syringae, Ps. viridiflava, and Ps. cannabina) and 8 Gram-negative bacteria from three other genera (Photorhabdus, Aeromonas, and Paludibacterium). In the alignment of the predicted primary amino acid sequences used for the phylogenetic analyses, both highly conserved and nonconserved parts of the toxin were discovered among the various species. Further comparative studies of the predicted ExoU homologs should provide us with more detailed information about the unique characteristics of the Ps. aeruginosa ExoU toxin.
Project description:The taxonomic affiliation of Pseudomonas isolates is currently assessed by using the 16S rRNA gene, MultiLocus Sequence Analysis (MLSA), or whole genome sequencing. Therefore, microbiologists are facing an arduous choice, either using the universal marker, knowing that these affiliations could be inaccurate, or engaging in more laborious and costly approaches. The rpoD gene, like the 16S rRNA gene, is included in most MLSA procedures and has already been suggested for the rapid identification of certain groups of Pseudomonas. However, a comprehensive overview of the rpoD-based phylogenetic relationships within the Pseudomonas genus is lacking. In this study, we present the rpoD-based phylogeny of 217 type strains of Pseudomonas and defined a cutoff value of 98% nucleotide identity to differentiate strains at the species level. To validate this approach, we sequenced the rpoD of 145 environmental isolates and complemented this analysis with whole genome sequencing. The rpoD sequence allowed us to accurately assign Pseudomonas isolates to 20 known species and represents an excellent first diagnostic tool to identify new Pseudomonas species. Finally, rpoD amplicon sequencing appears as a reliable and low-cost alternative, particularly in the case of large environmental studies with hundreds or thousands of isolates.
Project description:Pseudomonas spp. are able to colonize a large variety of environments due to their wide adaptability which is also associated with an N-acyl homoserine lactone (AHL) gene regulation mechanism called quorum sensing (QS). In this article we present a systematic overview of the genomic arrangement patterns of quorum sensing genes found in Pseudomonas and compare the topologies with those found in other bacterial genomes. We find that the topological arrangement of QS genes is more variable than previously thought but there are a few unifying features that occur in many of the topological arrangements. We hypothesize that the negative regulators of QS that are often found between the canonical luxR/ and luxI-family genes may be crucial for stabilizing the output of QS circuits.
Project description:Pseudomonas syringae is pathogenic in a wide variety of plants, causing diseases with economic impacts. Pseudomonas syringae pathovars produce several toxins that can function as virulence factors and contribute to disease symptoms. These virulence factors include antimetabolite toxins, such as tabtoxin, phaseolotoxin and mangotoxin, which target enzymes in the pathways of amino acid metabolism. The antimetabolite toxins are generally located in gene clusters present in the flexible genomes of specific strains. These gene clusters are typically present in blocks of genes that appear to be integrated into specific sites in the P. syringae core genome. A general overview of the genetic organization and biosynthetic and regulatory functions of these genetic traits of the antimetabolite toxins will be given in the present work.
Project description:We report a study conducted to investigate the variation on gene expression of the pathogenic fungus Aspergillus fumigatus upon co-cultivation with the pathogenic bacterium Pseudomonas aeruginosa. The study was conducted by investigating the gene expression variation at different time points (45, 90 and 180 minutes after co-incubation). As control, we used data obtained by cultivating the fungus either without bacteria, or with heat-inactivated Pseudomonas. Overall design: Examination of Aspergillus fumigatus co-cultivated with Pseudomonas aeruginosa.