Effekten av stressfaktorer i matkjeden på Listeria monocytogenes

The work presented in this thesis was carried out at Section for Food Bacteriology, Unit Food Safety, Antimicrobial Resistance and Zoonoses, Research section for Food Safety and Animal Health at the Veterinary Institute and Department of Paraclinical Sciences at the Faculty of Veterinary Medicine NMBU in Oslo. The work was carried out between 2014 and 2019.Listeria monocytogenes is the causative agent of food-borne listeriosis, a disease often transmitted by contaminated Ready-To-Eat (RTE) food. Immunosuppressed individuals, fetuses, and the elderly are at higher risk of developing a lethal form of listeriosis. Despite preventive actions taken against L. monocytogenes contamination of food, human listeriosis is still a food safety challenge. L. monocytogenes is a robust ubiquitous soil bacterium that is highly resistant to several stressors in the food chain, from farm to the human host. It is therefore difficult to eradicate it from raw food material and food processing environments. However, avoiding contamination and subsequent inhibiting growth of the bacterium in the food are important and highly prioritized preventive measures taken by the food industry. L. monocytogenes’ ability to persist in the food environment and to cause severe disease makes it a costly foodborne pathogen to control both in the food industry and in the society. This PhD project has explored how L. monocytogenes copes with a selected set of stressors present in the food, in the environment and in the human host, focusing on the aim of increasing food safety.L. monocytogenes er årsaken til matbåren listeriose, en sykdom som ofte er forårsaket av spiseklar mat (Ready-To-Eat, RTE) som er forurenset med L. monocytogenes. Individer med nedsatt immunforsvar, fostre og eldre har høyere risiko for å få listeriose med dødelig utfall. Til tross for forebyggende tiltak mot L. monocytogenes i mat, er listeriose hos mennesker fortsatt en utfordring for mattryggheten. L. monocytogenes er en robust bakterie som finnes nesten overalt og som er svært resistent mot mange stressfaktorer i matkjeden. Den er derfor vanskelig å eliminere fra råvarer og fra matproduskjonsmiljøer. Til tross for dette er det høyt prioritert av matindustrien å iverksette forebyggende tiltak for å redusere forurensning med L. monocytogenes og påfølgende vekst av denne bakterien i matproduktene. L. monocytogenes evne til å persistere i miljøet og dens evne til å forårsake alvorlig sykdom gjør at den er en kostbar matbåren bakterie for både matindustrien og for samfunnet. Med mål om å styrke mattryggheten har dette PhD prosjektet undersøkt hvordan L. monocytogenes håndterer ulike stressfaktorer som finnes i mat, i miljøet og i mennesket som vertsorganisme.Veterinærinstitutte

Transcriptomic and proteomic analysis of the virulence inducing effect of ciprofloxacin on enterohemorrhagic Escherichia coli

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The effect of food chain stressors on Listeria monocytogenes

Listeria monocytogenes is the causative agent of food-borne listeriosis, a disease often transmitted by contaminated Ready-To-Eat (RTE) food. Immunosuppressed individuals, fetuses, and the elderly are at higher risk of developing a lethal form of listeriosis. Despite preventive actions taken against L. monocytogenes contamination of food, human listeriosis is still a food safety challenge. L. monocytogenes is a robust ubiquitous soil bacterium that is highly resistant to several stressors in the food chain, from farm to the human host. It is therefore difficult to eradicate it from raw food material and food processing environments. However, avoiding contamination and subsequent inhibiting growth of the bacterium in the food are important and highly prioritized preventive measures taken by the food industry. L. monocytogenes’ ability to persist in the food environment and to cause severe disease makes it a costly foodborne pathogen to control both in the food industry and in the society. This PhD project has explored how L. monocytogenes copes with a selected set of stressors present in the food, in the environment and in the human host, focusing on the aim of increasing food safety

Hardware-in-the-Loop Simulation of Vehicle-Manipulator Systems for Physical Interaction Tasks

Hardware-in-the-loop simulation (HILS) allows a more realistic evaluation of control approaches than what is possible with pure software simulations, but without the actual complexity of the complete system. This is important for some complex systems such as orbital robots, where testing of the system is typically not possible after its launch, and an on-ground replica is used to validate the performance of such a system. In this article, an impedance-matching approach is presented to match the end-effector dynamics of a fixed-base robot manipulator with that of a target vehicle-manipulator system (VMS), while taking into account the redundant nullspace dynamics in a connected real-time simulation framework. This approach ensures that the forces and torques exerted by the system on the environment matches with that of the simulated system. The contact wrenches used in our approach are not obtained from numerical simulations, but rather from real physical interaction, which is one of the main advantages of our approach. The effectiveness of our method is validated by demonstrating various physical interaction tasks with the environment, using a suspended aerial manipulator as the target system