Project description:Listeria monocytogenes is a food-borne pathogen and the causative agent of listeriosis, an infection which typically arises through the consumption of contaminated foodstuffs. L. monocytogenes is a psychotrophic and facultatively anaerobic; properties which permit growth under refrigeration conditions and within modified atmosphere packaging. Through transcriptional changes L. monocytogenes is able to mount adaptive responses against stressors. Such responses typically cross protect against subsequent stresses.
Project description:In this study, RNA-seq was used to compare the transcriptomes of Listeria monocytogenes 10403S and H7858 and corresponding ΔsigB mutants under exposure to pH 5.5 with or without bile. RNA-seq was performed on all strains and conditions in four independent biological replicates. Indexed and purified cDNA libraries (12 libraries per strains) were loaded together onto an independent flow cell without any other samples; sequencing was carried out by running Hiseq 2500 (single-end, 100-bp per read). Reads alignment was carried out using the Burrows-Wheeler Aligner (BWA). Differential expression of genes in different strains and conditions was statistically assessed using the BaySeq method.
Project description:Protein extracts of Saccharomyces cerevisiae CEN.PK113-7D cultivated in chemostats under different conditions. Representative samples containing aliquots of all conditions were spiked with UPS2 standard (Sigma) to estimate absolute values in fmol. The conditions for Saccharomyces cerevisiae CEN.PK113-7D are: T2- Standard condition : 30°C, pH 5.5 T3- High temperature: 36°C, pH 5.5 T4- Low pH: 30°C, pH 3.5 T5- Osmotic stress : 30°C, pH 5.5, 1M KCl T6- Anaerobic condition Furthermore, representative samples pooling aliquots of each condition are indicated as "bulk" samples. These samples were spiked with UPS proteins. A validation step was carried out by spiking 4 external proteins at known concentrations within the yeast and UPS proteins mixture
Project description:Listeria monocytogenes is a gram-positive, facultative anaerobe food-borne pathogen that is the causative agent of listeriosis. Upon ingestion, L. monocytogenes is subjected to a variety of non-specific host defenses such as bile. The main component of bile is bile salts which is known to be bactericidal through inducing DNA damage, oxidative damage, membrane instability, and protein misfolding. Previous studies have focused mainly on aerobic conditions; however the human GI tract is an environment ranging from microaerophilic to anaerobic. The bile salt hydrolase, an enzyme known to reduce toxicity of bile through hydrolysis, has been shown to have an increase in activity under anaerobic conditions. Therefore, the purpose of this study was to determine the effect of oxygen on bile resistance and determine the bile specific proteome that is responsible for this. To do this, we performed survival assays on virulent strains: F2365, 10403S, EGDe and avirulent strain, HCC23. Results showed an increase in viability for all virulent strains when exposed to porcine bile under anaerobic conditions. Interestingly, an increase in resistance was seen in HCC23 only under aerobic conditions. We then used a total proteomic analysis approach to compare the bile specific proteome under both aerobic and anaerobic conditions. Results showed many difference between all strains including an increase in abundance of proteins associated with stress responses, repair, cell morphology, and cell division under anaerobic conditions. Response to bile salt stress showed to be strain dependent. This study not only identified proteins responsible for L. monocytogenes bile resistance but also differerences between aerobic and anaerobic conditions thus suggesting that oxygen availability is not only a stressor but in some way providing assistance to overcoming bile salts.
2017-05-03 | PXD002243 | Pride
Project description:Transcriptomic analysis of Listeria monocytogenes in response to bile under aerobic conditions at pH 7.5