Project description:Full title: Probing the pan genome of a foodborne bacterial pathogen Listeria monocytogenes: Implications for its niche adaptation, pathogenesis, and evolution Listeria monocytogenes is a foodborne bacterial pathogen well known for adaptability to diverse environmental and host niches, and a high fatality rate among infected, immuno-compromised individuals. Three genetic lineages have been identified within this species. Strains of genetic lineages I and II account for more than ninety percent of foodborne disease outbreaks worldwide, whereas strains from genetic lineage III are rarely implicated in human infectious for unknown, yet intriguing, reasons. Here we have probed the genomic diversity of 26 L. monocytogenes strains using both whole-genome sequences and a novel 385,000 probe pan-genome microarray, fully tiling the genomes of 20 representative strains. Using these methods to identify genes highly conserved in lineages I and II but rare in lineage III, we have identified 86 genes and 8 small RNAs that play roles in bacterial stress resistance, pathogenicity, and niche, potentially explaining the predominance of L. monocytogenes lineages I and II in foodborne disease outbreaks. Extending gene content analysis to all lineages revealed a L. monocytogenes core genome of approximately 2,350 genes (80% of each individual genome) and a pan-genomic reservoir of >4,000 unique genes. Combined gene content data from both sequences and arrays was used to reconstruct an informative phylogeny for the L. monocytogenes species that confirms three distinct lineages and describes the relationship of 9 new lineage III genomes. Comparative analysis of 18 fully sequenced L. monocytogenes lineage I and II genomes shows a high level of genomic conservation and synteny, indicative of a closed pan-genome, with moderate domain shuffling and sequence drift associated with bacteriophages is present in all lineages. In contrast with lineages I and II, notable genomic diversity and characteristics of an open pan-genome were observed in the lineage III genomes, including many strain-specific genes and a more complex conservation pattern. This indicates that the L. monocytogenes pan-genome has not yet been fully sampled by genome sequencing, and additional sequencing of lineage III genomes is necessary to survey the full diversity of this intriguing species and reveal its mechanisms for adaptability and virulence. This is a Listeria monocytogenes pan-genome tilling array designed using PanArray algorithm. 9 experimental strains (F2-569, M1-002, F2-208, J2-071, J1-208, W1-111, W1-110, F2-524, F2-501) vs reference (EGD-e) strain.
Project description:CadC is the transcriptional regulator of CadA, an efflux pump conferring cadmium resistance. We previously showed that during in vivo infection, Listeria monocytogenes uses CadC to directly repress the expression of the LspB lipoprotein signal peptidase, avoiding the exposure of the lipoprotein LpeA to the host immune system, impairing inflammatory cytokine expression and promoting intramacrophage survival and virulence. Here, to assess if CadC could be a widespread virulence regulator, we searched for other genes regulated by CadC using Listeria monocytogenes tiling arrays.
Project description:Persistence of Listeria monocytogenes in retail deli environments is a serious food safety issue, potentially leading to cross-contamination of ready-to-eat foods such as deli meats, salads, and cheeses. We previously discovered strong evidence of L. monocytogenes persistence in delis across multiple states. We hypothesized that this was correlated with isolates’ innate characteristics, such as biofilm-forming capacity or gene differences.We further chose four isolates for RNA-sequencing analysis and compared their global biofilm transcriptome to their global planktonic transcriptome. Analysis of biofilm vs planktonic gene expression did not show the expected differences in gene expression patterns. Overall, L. monocytogenes persistence in the deli environment is likely a matter of poor sanitation and/or facility design, rather than isolates’ biofilm-forming capacity, sanitizer tolerance, or genomic content
Project description:Full title: Probing the pan genome of a foodborne bacterial pathogen Listeria monocytogenes: Implications for its niche adaptation, pathogenesis, and evolution Listeria monocytogenes is a foodborne bacterial pathogen well known for adaptability to diverse environmental and host niches, and a high fatality rate among infected, immuno-compromised individuals. Three genetic lineages have been identified within this species. Strains of genetic lineages I and II account for more than ninety percent of foodborne disease outbreaks worldwide, whereas strains from genetic lineage III are rarely implicated in human infectious for unknown, yet intriguing, reasons. Here we have probed the genomic diversity of 26 L. monocytogenes strains using both whole-genome sequences and a novel 385,000 probe pan-genome microarray, fully tiling the genomes of 20 representative strains. Using these methods to identify genes highly conserved in lineages I and II but rare in lineage III, we have identified 86 genes and 8 small RNAs that play roles in bacterial stress resistance, pathogenicity, and niche, potentially explaining the predominance of L. monocytogenes lineages I and II in foodborne disease outbreaks. Extending gene content analysis to all lineages revealed a L. monocytogenes core genome of approximately 2,350 genes (80% of each individual genome) and a pan-genomic reservoir of >4,000 unique genes. Combined gene content data from both sequences and arrays was used to reconstruct an informative phylogeny for the L. monocytogenes species that confirms three distinct lineages and describes the relationship of 9 new lineage III genomes. Comparative analysis of 18 fully sequenced L. monocytogenes lineage I and II genomes shows a high level of genomic conservation and synteny, indicative of a closed pan-genome, with moderate domain shuffling and sequence drift associated with bacteriophages is present in all lineages. In contrast with lineages I and II, notable genomic diversity and characteristics of an open pan-genome were observed in the lineage III genomes, including many strain-specific genes and a more complex conservation pattern. This indicates that the L. monocytogenes pan-genome has not yet been fully sampled by genome sequencing, and additional sequencing of lineage III genomes is necessary to survey the full diversity of this intriguing species and reveal its mechanisms for adaptability and virulence.
Project description:For bacteria in general and Listeria monocytogenes in particular, little is known about transcriptome diversity in comparison to the copious data on intraspecific genome diversity. The current study employed RNA sequencing to investigate the variation of transcript levels of conserved single copy genes from several perspectives including differences between lineages and correlation with previous classification of the virulence potential of clonal complexes based on epidemiological MLST data. Infection of G. mellonella, a surrogate host, also allowed a correlation analysis with virulence data experimentally determined in vivo.
2019-09-10 | GSE129537 | GEO
Project description:Genomic characterization of Listeria monocytogenes from RTE meat products and meat processing environments in Poland
| PRJNA629756 | ENA
Project description:Virulence potential of Listeria monocytogenes strains persisting in a meat processing plant of Central Italy
Project description:The Gram-positive bacterium Listeria monocytogenes is widely distributed in the environment and capable of causing food-borne infections in susceptible individuals. In this study, we investigated the cell envelope stress response in L. monocytogenes. Whole-genome transcriptional profiling was performed to investigate the response upon exposure to the cell wall antibiotic cefuroxime. Differential expression (≥ 2-fold difference) of 558 genes was observed, corresponding to 20% of the L. monocytogenes genome. The majority of genes strongly induced by cefuroxime exposure have cell envelope-related functions, including the dlt-operon, genes encoding penicillin-binding proteins, and members from the LiaRS regulon. The virulence-associated genes dacA and lmo2714 were up-regulated upon cefuroxime exposure, whereas PrfA-regulated virulence genes, required for invasion and intracellular replication, were repressed. A large overlap was observed between the cefuroxime stimulon and genes known to be induced in L. monocytogenes in blood and during intracellular infection, indicating that the cell envelope stress response is active at various stages of the infectious process. Genes involved in stress tolerance (htrA, ctc) and signal transduction (lisRK) were also found among the highly up-regulated genes. We analysed the roles of the two-component systems LisRK and CesRK, showing that activation of the most highly cefuroxime-induced genes was LisR- and CesR-dependent. Using genetic analyses, we showed that several genes of the cefuroxime stimulon contribute to the innate resistance of L. monocytogenes to cefuroxime and tolerance to other cell envelope-perturbing conditions. Collectively, these findings demonstrate central roles for LisRK and CesRK in orchestrating the cell envelope stress response in L. monocytogenes.
Project description:Listeria monocytogenes is a human, food-borne pathogen. Genomic comparisons between L. monocytogenes and Listeria innocua, a closely related non-pathogenic species, were pivotal in the identification of protein coding genes essential for virulence. However, no comprehensive comparison has focused on the non-coding genome. We used strand-specific cDNA sequencing to produce genome-wide transcription start site (TSS) maps for both organisms, and developed a publicly available integrative browser to visualize and analyze both transcriptomes in different growth conditions and genetic backgrounds. Our data revealed conservation across most transcripts, but significant divergence between the species in a subset of non-coding RNAs. In L. monocytogenes we identified 113 sRNAs and 70 asRNAs, significantly increasing the repertoire of non coding RNAs in this species. Remarkably, we identified a class of long antisense transcripts (lasRNAs) that overlap one gene while also serving as the 5M-bM-^@M-^Y UTR of the adjacent divergent gene. Experimental evidence suggests that lasRNAs transcription inhibits expression of one operon while activating the expression of another. Such lasRNA/operon structure, termed "excludon", might represent a novel form of regulation in bacteria. Construction of consensus TSS-maps in Listeria monocytogenes and Listeria innocua by applying 5'-end sequencing on samples in different conditions and genetic backgrounds.