Project description:Bacillus cereus is the second leading cause of collective food poisoning in France. B. cereus is also associated with severe clinical infections leading to patient death in 10% of the cases. The emergence of B. cereus as a foodborne and opportunistic pathogen has intensified the need to distinguish strains of public health concern. In this work, by performing a screen on a large collection of B. cereus strains of varying pathogenic potential, we identified genetic determinants capable of discriminating B. cereus strains inducing negative clinical outcomes. The combination of 4 biomarkers is sufficient to accurately discern clinical strains from harmless strains. Three of the biomarkers are located on the chromosome, with a fourth one identifying a plasmid carried by most pathogenic strains. A 50 kbp region of this plasmid promotes the virulence potential of these strains and could thus be defined as a new pathogenicity island of B. cereus. These new findings help in the understanding of B. cereus pathogenic potential and complexity and may provide tools for a better assessment of the risks associated with B. cereus contamination to improve patient health and food safety.
Project description:We performed RNAseq for gene expression analysis for six strains of Acinetobacter Baumannii isolated from blood samples (defined as strains 1, 2, 3, 4 and 6) of patients hospitalized at the University Hospital \\"San Giovanni di Dio e Ruggi d'Aragona\\" (Salerno, Italy)
Project description:Pathogenic species belonging to Bacillus cereus sensu lato group possess a high evolutionary advantage in the environment and in food matrices thanks to their capacity to survive as silent spores to harsh environmental insults and grow at relatively low temperatures. Ready to re-heat products are at severe risk for contamination by members of Bacillus cereus s.l. group if not stored at proper conditions. In this work, the goal was to assess, by means of a genome-wide transcriptional assay, the isolated strain Bacillus cereus UC10070 gene expression behind the process of spore germination and consequent outgrowth in an artificially contaminated vegetable-based food model. A vegetable food model subjected to a heat treatment was determined to present favourable conditions for spores germination. Microscopic analyses together with OD measurements were applied to select the key steps of B. cereus cell cycle to be used for the microarray analysis. Using this approach we found a total of 1,646 probe sets differentially expressed and modulated during the entire B. cereus life cycle in the vegetable foodstuff.
Project description:We isolated an atmospheric contaminant, subsequently identified as a new strain of Bacillus mobilis, which showed a novel, robust, inducible filamentous sliding motility and completely colonized a bacterial culture plate in less than 48 h under some conditions. This flagella-independent sliding motility was characterized by long filamentous cells at the expanding edge, and was induced when cells were inoculated onto lawns of metabolically inactive Campylobacter jejuni cells, heat killed bacterial biomass, and milk or blood dried onto agar plates. Phosphatidylcholine (PC), bacterial membrane components, and sterile human fecal extracts were sufficient to induce filamentous expansion. Screening of eight other Bacillus spp. (five from the B. cereus group and three other Bacillus spp.) showed that filamentous motility was conserved amongst B. cereus group species to varying degrees. RNAseq of filamentously expanding cells collected from PC and milk lawn plates in comparison to rod-shaped cells from control plates revealed that genes related to metabolism, ion and amino acid transport were differently regulated, genes controlling sporulation were reduced, and some virulence genes (e.g., hblA/B/C/D and plcR) were increased. We hypothesize that the robust and conserved nature of filamentous motility in pathogenic B. cereus group species can enhance bacterial colonization during host colonization.
Project description:This SuperSeries is composed of the following subset Series: GSE13711: Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 14579 GSE13729: Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 10987 Refer to individual Series
Project description:The goal of this study is the discovery of (a) meaningful phylogenomic relationships among members of this B. cereus/B. anthracis group, and (b) reliable gene-phenotype associations, e.g. recognition of links between genomic traits and the ability of certain strains to cause various forms of disease. We also tried to elucidate genome evolution aspects that may lead to the emergence of variants that are capable (or have the potential) of causing anthrax-like disease. This large-scale comparative genomics approach is unprecedented for this taxonomic group. Dr. A. Hoffmaster (CDC) provided the PFGRC with 73 B. cereus and B. anthracis isolates from the CDC culture collection. Of these, 27 were isolated from patients with severe or systemic disease; ten isolates of this group were obtained from patients (welding factory workers) with anthrax-like disease or from the environment near their workplace. Another set of 26 represented isolates from food-born illnesses. Of the 26 gastrointestinal disease isolates (GIDI), 10 were obtained from patients with diarrhea, whereas another set of 10 had been shown to harbor the emetic (vomit) toxin gene by PCR. The rest of the group consisted of 20 isolates with various phenotypes. All strains were screened for their genomic content using the B. cereus/B. anthracis species microarray.
Project description:Pathogenic species belonging to Bacillus cereus sensu lato group possess a high evolutionary advantage in the environment and in food matrices thanks to their capacity to survive as silent spores to harsh environmental insults and grow at relatively low temperatures. Ready to re-heat products are at severe risk for contamination by members of Bacillus cereus s.l. group if not stored at proper conditions. In this work, the goal was to assess, by means of a genome-wide transcriptional assay, the isolated strain Bacillus cereus UC10070 gene expression behind the process of spore germination and consequent outgrowth in an artificially contaminated vegetable-based food model. A vegetable food model subjected to a heat treatment was determined to present favourable conditions for spores germination. Microscopic analyses together with OD measurements were applied to select the key steps of B. cereus cell cycle to be used for the microarray analysis. Using this approach we found a total of 1,646 probe sets differentially expressed and modulated during the entire B. cereus life cycle in the vegetable foodstuff. RNA was isolated from the dormant spores (DS), germinating spores at 40 minutes (GSP), early-log phase at 2h (C2h) and late log phase cells at 12 hours (C12h) after thermal treatment of B. cereus UC10070 previously isolated froma biofilm on a spoiled vegetable-based puree. There were 3 biological replicates (independent cultures) for each condition. Complete genome sequence of B. thuringiensis sv konkukian str. 97-27 (NCBI Reference Sequence: NC_005957.1) was chosen for its high homology with B. cereus s.l. UC10070, to design probes corresponding to 5,197 genes spotted in duplicates onto ElectraSenseH 12K microarrays chip.
Project description:B. cereus RNA isolation were taken at OD 0.5 just before addition of 0.02 mg/mL EEC, and at 30 min of exposure. Water was added instead of EEC for control. Total RNA was isolated and we performed DNA microarray for genome-wide transcriptional analysis of B. cereus ATCC 14579 in the presence or absence of EEC. The microarray used in this study was custom-made B. cereus ATCC 14579 developed by Agilent Technologies (https://earray.chem.agilent.com/earray/). The B. cereus microarray design was based on the predicted chromosomal open reading frames (NCBI Accession No. AE016877). It targets the 5234 annotated CDS, three non-overlapping probes were designed, low-quality probes were eliminated, and finally 15242 could be spotted. Microarray data was normalized to 75th percentile and the difference was found to be significant by unpaired T-test (P = 0.05). Next, ratio changes of 2-fold (for up-regulated genes in the EEC stress condition) and 0.5-fold (for down-regulated genes in the EEC stress condition) were regarded as biologically significant. 596 were up-regulated and 495 were down-regulated.