Project description:transcriptional profiling of L. monocytogenes ctsR mutant under pressure treatment SUBMITTER_CITATION: Liu, Y., Huang, L., Joerger, R.D., Gunther, N.W. 2012. Genes that are involved in high hydrostatic pressure treatments in a Listeria monocytogenes Scott A ctsR deletion mutant. Journal of Microbial and Biochemical Technology. 4:050-056.
Project description:Transcriptional profling of a Listeria monocytogenes under pressure comparing ctsR mutant and wild type one condition (pressure 450 Moa, 3min) experiment, mutant vs. wild type, 2 biological replicates, two technical replicates
Project description:High hydrostatic pressure processing (HPP) is currently being used as a treatment for certain foods to control the presence of food-borne pathogens, such as Listeria monocytogenes. Genomic microarray analysis was performed to determine the effects of HPP on L. monocytogenes in order to understand how it responds to mechanical stress injury. Reverse transcriptase PCR analysis of tufB and rpoC indicated that the reduction of mRNA expression in HPP treated cells was dependent on intensity and time of the treatment. Treatments of 400 and 600 MPa for 5 min. on cells in the exponential growth phase though leading to partial or complete cellular inactivation still resulted in measurable relative differential gene expression. Gene set enrichment analysis indicated HPP induced increased expression of genes associated with DNA repair mechanisms, transcription and translation protein complexes, the septal ring, the general protein translocase system, flagella assemblage and chemotaxis, and lipid and peptidoglycan biosynthetic pathways. HPP on the other hand appears to suppress a wide range of energy production and conversion, carbohydrate metabolism, and virulence associated genes accompanied by strong suppression of the SigB and PrfA regulons. HPP also induced repression of genes negatively controlled by pleotrophic regulator CodY. HPP-induced cellular damage appears to lead to increased expression of genes linked to sections of the cell previously shown in bacteria to be damaged or altered during HPP exposure and suppression of gene expression associated with cellular growth processes and virulence. Keywords: Stress response
Project description:transcriptional profiling of L. monocytogenes ctsR mutant under pressure treatment Two-condition experiment: mutant under pressure (450Mpa, 3min) vs. normal condition, two biological replicates.
Project description:The formation of Listeria monocytogenes biofilms contributes to persistent contamination in food processing facilities. A microarray comparison of L. monocytogenes between the transcriptome of the strong biofilm forming strain (Bfms) Scott A and the weak biofilm forming (Bfmw) strain F2365 was conducted to identify genes potentially involved in biofilm formation. Among 951 genes with significant difference in expression between the two strains, a GntR-family response regulator encoding gene (LMOf2365_0414), designated lbrA, was found to be highly expressed in Scott A relative to F2365. A Scott A lbrA-deletion mutant, designated AW3, formed biofilm to a much lesser extent as compared to the parent strain by a rapid attachment assay and scanning electron microscopy. Complementation with lbrA from Scott A restored the Bfms phenotype in the AW3 derivative. A second microarray assessment using the lbrA deletion mutant AW3 and the wild type Scott A revealed a total of 304 genes with expression significantly different between the two strains, indicating the potential regulatory role of LbrA in L. monocytogenes. A cloned copy of Scott A lbrA was unable to confer enhanced biofilm forming potential in F2365, suggesting that additional factors contributed to weak biofilm formation by F2365. Findings from the study may lead to new strategies to modulate biofilm formation. Two comparisons were performed between 1) strong biofilm former Listeria monocytogenes strain ScottA versus weak biofilm former Listeria monocytogenes strain F2365; 2) Listeria monocytogenes ScottA LbrA deletion mutant strain versus Listeria monocytogenes ScottA. Four replicates were loaded for the first comparison and two replicates were loaded for the second comparison.
Project description:Several Toll-like receptors are activated by Listeria monocytogenes infection, resulting in the activation of MyD88 dependent signaling pathway. However, the negative role of MyD88 in gene expresson is unclear. To address this, we performed microarray analysis of mRNAs from WT or MyD88-/- peritoneal macrophages infected with Listeria monocytogenes.
Project description:Listeria monocytogenes strain 10403S has been studied extensively for stress response activity toward multiple stressors (acid, osmotic, cold, high temperature, etc.) as well as multiple stress regulons (SigB, CtsR, HrcA, etc.). Here we aimed to determine the transcriptional response of Listeria monocytogenes in early log phase towards the strong oxidative stress imposed by ClO2. The elucidation of such a response allows for further a more completel understanding of the mechanism of inactivation by sanitizers, specifically ClO2.