Project description:Cultivation based analyses were used to determine the resistance of a set of 140 Listeria monocytogenes strains to weak organic acids. Strains of lineage I tended to exhibit greater overall resistant to four different organic acids compared to lineage II strains. Resistant strains also possessed higher survival levels following challenge to pH 2.4 compared to sensitive strains. Transcriptomic analyses were performed to determine genetic responses relevant to growth at mildly acidic conditions (pH 5.0) and to the presence of sodium diacetate. Lineage I and II strain representatives, clinical strain ATCC 19115 and food isolate FW04/0023, were found to exhibit similar transcriptomic changes when habituated to pH 5.0 in brain heart infusion broth (BHIB) relative to growth at pH 7.2 though considerably more divergent responses were detected when 21 mM sodium diacetate was present. Homogeneity in acid habituation-related gene expression was reflected in relatively homogenous SigB, PrfA, HrCA and CodY regulon expression responses. In the presence of sodium diacetate, SigB and PrfA regulon genes found to be upregulated in sigB and prfA null mutants were overall repressed but SigB dependent-gene activation was not evident. L. monocytogenes strains responses to sodium diacetate were observed in different expression trends amongst various functionally-related gene sets and in particular the expression of the PrfA, Atp, Kdp, Cob, Pdu, Eut and Dlt operons; iron transporter and heat shock-related proteins. The results suggest there is diversity in the specific responses to weak organic acids and subsequent cytosolic acidification amongst L. monocytogenes strains though the acid tolerance response itself manifests as a more conserved set of expression responses.
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.
Project description:Listeria monocytogenes cells (strain LI0521) were digested with trypsin for the identification of surface proteins. The supernatant was filter-sterilized and subjected to identification by LC-MS/MS. Concurrently secreted or shed proteins were identified by isolating filter-sterilized supernatants following incubation of L. monocytogenes cells in buffer without trypsin. This was followed by trypsin digest of the sterilized supernatant and identification by LC-MS/MS.
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. Independent RNA isolations were performed for strain 10403S with and without exposure to ClO2 from cells grown to early log phase. Four biological replicates were used in competitive whole-genome microarray experiments. For each set of hybridizations, RNA from a control sample of Listeria monocytogenes was hybridized with RNA from a culture of L. monocytogenes following exposure to ClO2. Dye swapping was performed for the four replicates to mitigate any concerns of dye bias.
Project description:Listeria monocytogenes is the ubiquitous food-borne pathogen which causes listeriosis, a disease with a high mortality rate, mostly transmitted through contaminated ready-to-eat foods (EFSA, 2018). To better understand the systemic response of such microorganism exposed at three environmental factors (T, pH and NaCl), the proteome of a L. monocytogenes strain, which was isolated from a meat product (Coppa di testa) linked to a listeriosis outbreak occurred in Marche region (Italy) in 2016, was investigated in order to identify differences in its protein patterns.
Project description:Comparisons of gene expression profiles of human hepatocytes (HepG2) infected or not by the bacterium Listeria monocytogenes (strain EGD-e) for 72 hours and analysed by RNA-seq
Project description:Comparisons of gene expression profiles of human hepatocytes (Huh7) infected or not by the bacterium Listeria monocytogenes (strain EGD-e) for 72 hours and analysed by RNA-seq
Project description:These studies were designed to examine the acute Listeria monocytogenes transcriptional response to mammalian (porcine) bile. Triplicate WT Listeria monocytogenes (strain 10403S) were grown to mid-log in BHI at 37 °C. Samples were divided, and either treated or not treated by addition of porcine bile (Sigma, to 1% final) for 30 minutes.