Project description:Time course study of the mouse infection by comparing the genomic transcriptional patterns of Listeria monocytogenes EGDe grown under laboratory conditions (exponential growth phase) with that of in vivo-grown bacteria (in mouse spleens) over three days of infection. Time course study of the mouse infection by comparing the genomic transcriptional patterns of Listeria monocytogenes EGDe grown under laboratory conditions (exponential growth phase) with that of in vivo-grown bacteria (in mouse spleens) over three days of infection.
Project description:Time course study of the mouse infection by comparing the genomic transcriptional patterns of Listeria monocytogenes EGDe grown under laboratory conditions (exponential growth phase) with that of in vivo-grown bacteria (in mouse spleens) over three days of infection.
Project description:Gene expression changes in L. monocytogenes EGDe during lag-phase associated cold acclimation were succesfully defined through expression profiling
Project description:Transcriptional profile of wild type L. monocytogenes (EGDe) and a pycA mutant strain was compared on growth in BHI. The human pathogen L. monocytogenes is a facultatively intracellular bacterium that survives and replicates in the cytosol of many mammalian cells. The listerial metabolism, especially under intracellular conditions , is still poorly understood. Recent studies analyzed the carbon metabolism of L. monocytogenes by the 13C-isotopologue perturbation method in a defined minimal medium containing [U-13C6]glucose. It was shown that these bacteria produce oxaloacetate mainly by carboxylation of pyruvate due to an incomplete tricarboxylic acid cycle. Here we report that a pycA insertion mutant defective in pyruvate carboxylase (PYC) still grows, albeit at a reduced rate, in BHI medium, but is unable to multiply in a defined minimal medium with glucose or glycerol 36 as carbon source. Transcriptional profiling was performed on the pycA mutant and the wild type strain grown in BHI to get a closer insight into the effect of the pycA mutation in Listeria monocytogenes.
Project description:The phenotypic and gene expression traits conferred by the alternative sigma factor protein σL in the food-borne pathogen L. monocytogenes were investigated. σL was shown to be important for the efficient growth of this pathogen exposed to food preservative measures such as low storage temperatures, elevated osmolarity and acidity. Based on high throughput phenotypic analysis, σL function was also found to be protective in L. monocytogenes EGDe cells exposed to several antimicrobial compounds including some of the antibiotics currently applied in listeriosis treatment. The expression of flagella genes and motility were significantly compromized upon loss of σL function. A comparative transcriptome analysis of exponential growth EGDe wild type and sigL null cells unveiled 394 genes that are positively controlled through σL dependent transcriptional regulation mechanisms in this bacterium during growth at low (3°C) and optimized (37°C) temperature conditions. Genes identified indicate that σL is a pleitropic transcription regulator mediating positive expression control of genes involved in diverse cellular processes including protein synthesis, molecular transport, energy metabolism, respiration, transcription regulation, metabolite biosynthesis, and cell envelope composition modification. Overall our observations have revealed that the loss of σL function leads to extensive gene expression defects in L. monocytogenes EGDe cells, and these are consistent with compromized nutrient assimilation, energy metabolism, protein synthesis, and metabolite biosynthesis processes as well as altered cell envelope composition and motility. Numerous gene expression changes imposed by σL loss in EGDe are thus also consistent with pleiotropic phenotypic defects detected in the L. monocytogenes EGDe ∆sigL strain.