Phylogenetic and Phenotypic Analyses of a Collection of Food and Clinical Listeria monocytogenes Isolates Reveal Loss of Function of Sigma B from Several Clonal Complexes.

To understand the molecular mechanisms that contribute to the stress responses of the important foodborne pathogen Listeria monocytogenes, we collected 139 strains (meat,  = 25; dairy,  = 10; vegetable,  = 8; seafood,  = 14; mixed food,  = 4; and food processing environments,  = 78), mostly isolated in Ireland, and subjected them to whole-genome sequencing. These strains were compared to 25 Irish clinical isolates and 4 well-studied reference strains. Core genome and pan-genome analysis confirmed a highly clonal and deeply branched population structure.

Solar irradiance limits the long-term survival of Listeria monocytogenes in seawater.

Unlabelled: Seafood has often been implicated in outbreaks of food-borne illness caused by Listeria monocytogenes but the source of contamination is usually not known. In this study we investigated the possibility that this pathogen could survive in seawater for an extended time period. Freshly collected seawater samples were inoculated with 1 × 10  CFU per ml of L.

A 3-year multi-food study of the presence and persistence of Listeria monocytogenes in 54 small food businesses in Ireland.

The problem of assessing the occurrence of the food-borne pathogen Listeria monocytogenes in the food chain, and therefore the risk of exposure of the human population, is often challenging because of the limited scope of some studies. In this study the occurrence of L. monocytogenes in food from four major food groups, dairy products, meats, seafood and vegetables, and associated food processing environments in Ireland was studied over a three-year period.

The Role of Stress and Stress Adaptations in Determining the Fate of the Bacterial Pathogen in the Food Chain.

The foodborne pathogen is a highly adaptable organism that can persist in a wide range of environmental and food-related niches. The consumption of contaminated ready-to-eat foods can cause infections, termed listeriosis, in vulnerable humans, particularly those with weakened immune systems. Although these infections are comparatively rare they are associated with high mortality rates and therefore this pathogen has a significant impact on food safety.

Blue-Light Inhibition of Listeria monocytogenes Growth Is Mediated by Reactive Oxygen Species and Is Influenced by σB and the Blue-Light Sensor Lmo0799.

Unlabelled: Listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein Lmo0799, leading to activation of the general stress response sigma factor SigB (σ(B)). In this study, we investigated the physiological response of this foodborne pathogen to blue light. We show that blue light (460 to 470 nm) doses of 1.