Project description:Survival of the foodborne pathogen Listeria monocytogenes in acidic environments (e.g., stomach and low pH foods) is vital to its transmission. L. monocytogenes grows at temperatures as low as 2°C, and refrigerated, ready-to-eat foods have been sources of L. monocytogenes outbreaks. The purpose of this study was to determine whether growth at a low temperature (i.e., 7°C) affects the response of L. monocytogenes to sudden acid shock.
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.
2022-08-12 | PXD033519 | Pride
Project description:Listeria in a variety of foods and environmental surfaces
Project description:Survival of the foodborne pathogen Listeria monocytogenes in acidic environments (e.g., stomach and low pH foods) is vital to its transmission. L. monocytogenes grows at temperatures as low as 2M-BM-0C, and refrigerated, ready-to-eat foods have been sources of L. monocytogenes outbreaks. The purpose of this study was to determine whether growth at a low temperature (i.e., 7M-BM-0C) affects the response of L. monocytogenes to sudden acid shock. A full genome microarray was used to determine changes in L. monocytogenes 10403S gene expression after exposure to acidified brain-heart infusion (BHI; pH 3.5) for 5 or 15 min. To determine changes in gene transcription after acid treatment, separate competitive hybridizations were performed between cDNA from untreated cells (grown at 7M-BM-0C or 37M-BM-0C to log or stationary phase) and (i) cells acid treated for 5 min or (ii) cells acid treated for 15 min. For L. monocytogenes grown to log or stationary phase, competitive hybridizations were performed between total cDNA from non-acid-treated cells grown to 7M-BM-0C and non-acid-treated cells grown to 37M-BM-0C to determine baseline differences in gene transcription between growth temperatures prior to acid treatment. For each experiment, four biological replications were completed. Hybridizations were carried out with dye swapping (i.e., for each comparison, each cDNA from each condition was labeled with each dye exactly twice) to help minimize dye incorporation bias.
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:Human listeriosis cases are due to the ingestion of contaminated foods with the pathogenic bacteria Listeria monocytogenes. The reduction of water availability in food workshops by decreasing the air relative humidity (RH) is one strategy to improve the control of bacterial contamination. This study aims to develop and implement an MSI approach on L. monocytogenes biofilms and proof of concept using a dehumidified stress condition. MSI allowed examining the distribution of low molecular weight proteins within the biofilms subjected to a dehumidification environment, mimicking the one present in a food workshop (10°C, 75% RH). Furthermore, a LC-MS/MS approach was made to link the dots between MSI and protein identification. Five identified proteins were assigned to registered MSI m/z, including two cold-shock proteins and a ligase involved in cell wall biogenesis.
Project description:Total blood white blood cells from a FPIES subject were treated with individual treatmens of 2 foods that were safe for the subject (pear and breast milk), two foods that were triggers (quinoa and sweet potato), and 19 foods of unknown status for the subject. These treatments were compared to LPS treatment and untreated.
