Stress Response Mechanisms Of Bacterial Pathogens

A critical factor for bacterial survival in any environment is the ability to sense and respond appropriately to insults that cause stress to the cell, threatening its survival. Most of these stressors first affect the outer surface of the bacterial cell, are sensed in some way, and defense measures are enacted in response. If the bacteria successfully respond to an encountered stress, they survive and multiply. If they are unsuccessful or inefficient in their response, it can result in death. Efficiently responding to factors that induce stress is especially important for bacteria that inhabit environments that are constantly changing, or for those that inhabit more than one biological niche. In addition, bacterial species that associate with humans and other organisms must be able to overcome stresses that are produced by the host immune response in order to colonize and cause disease. The wide variety of stressors encountered by bacteria has resulted in countless strategies that are used by pathogens to overcome these insults, which we continue to identify. Clearly, a better understanding of these stress response mechanisms may be useful for developing new strategies to combat bacteria that cause certain infectious diseases. This Research Topic aims to highlight our increasing understanding of mechanisms by which bacteria sense and respond to stresses encountered in the host or other environments. Examples of stress response mechanisms of interest include, but are not limited to those that respond to antimicrobials, host immune responses, or environmental changes.

Food-borne bacterial pathogens encounter a number of stressors during food processing and preservation. More and more pathogens are able to adapt their physiological properties and/or genetic expression to survive these stressors and pose a risk to food safety and public health. This book provides the reader with a comprehensive overview of common food processing-associated stressors (e.g., heat, cold, acid, osmosis, and oxidation) and deals with the molecular basis of the respective bacterial stress response mechanisms (e.g., viable but nonculturable state, biofilm formation, sporulation, and cross-protection response). Additionally, various chapters cover the response mechanisms of foodborne pathogens to emerging nonthermal sterilisation technologies such as ultrasound, high-pressure processing, pulsed electric fields, ultraviolet light, irradiation and phytochemicals. Through this book we also learn about future prospects for the efficient control of stress adaption in foodborne pathogens to ensure maximum consumer safety. This book offers a valuable resource for researchers, graduate students, food process engineers and product developers in the fields of food science and microbiology.

The ability of pathogenic bacteria to adapt to various chemical, biochemical and physical conditions within the human host and their ability to respond to stresses generated in these environments is a central feature of infectious diseases and the outcome of bacterial infection. This book covers the key aspects of this rapidly developing field, including the generation of stresses by the host immune system, bacterial response to reactive chemicals, and adaptation to environmental conditions of anatomical niches such as the gut, mouth and urogenital tract. It also addresses the increasing impor.

Throughout the food processing chain and after ingestion by the host, food associated bacteria have to cope with a range of stress factors such as thermal and/or non-thermal inactivation treatments, refrigeration temperatures, freeze-drying, high osmolarity, acid pH in the stomach or presence of bile salts in the intestine, that threaten bacterial survival. The accompanying plethora of microbial response and adaptation phenomena elicited by these stresses has important implications for food technology and safety. Indeed, while resistance development of pathogenic and spoilage microorganisms may impose health risks for the consumer and impart great economic losses to food industries, reduced survival of probiotic bacteria may strongly compromise their claimed health benefit attributes. As a result, substantial research efforts have been devoted in the last decades to unravel the mechanisms underlying stress response and resistance development in food associated microorganisms in order to better predict and improve (i) the inactivation of foodborne pathogens and spoilage microorganisms on the one hand and (ii) the robustness and performance of beneficial microorganisms on the other. Moreover, the recent implementation of system-wide omics and (single-)cell biology approaches is greatly boosting our insights into the modes of action underlying microbial inactivation and survival. This Research Topic aims to provide an avenue for dissemination of recent advances within the field of microbial stress response and adaptation, with a particular focus not only on food spoilage and pathogenic microorganisms but also on beneficial microbes in foods.

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Bacteria in various habitats are subject to continuously changing environmental conditions, such as nutrient deprivation, heat and cold stress, UV radiation, oxidative stress, dessication, acid stress, nitrosative stress, cell envelope stress, heavy metal exposure, osmotic stress, and others. In order to survive, they have to respond to these conditions by adapting their physiology through sometimes drastic changes in gene expression. In addition they may adapt by changing their morphology, forming biofilms, fruiting bodies or spores, filaments, Viable But Not Culturable (VBNC) cells or moving away from stress compounds via chemotaxis. Changes in gene expression constitute the main component of the bacterial response to stress and environmental changes, and involve a myriad of different mechanisms, including (alternative) sigma factors, bi- or tri-component regulatory systems, small non-coding RNA’s, chaperones, CHRIS-Cas systems, DNA repair, toxin-antitoxin systems, the stringent response, efflux pumps, alarmones, and modulation of the cell envelope or membranes, to name a few. Many regulatory elements are conserved in different bacteria; however there are endless variations on the theme and novel elements of gene regulation in bacteria inhabiting particular environments are constantly being discovered. Especially in (pathogenic) bacteria colonizing the human body a plethora of bacterial responses to innate stresses such as pH, reactive nitrogen and oxygen species and antibiotic stress are being described. An attempt is made to not only cover model systems but give a broad overview of the stress-responsive regulatory systems in a variety of bacteria, including medically important bacteria, where elucidation of certain aspects of these systems could lead to treatment strategies of the pathogens. Many of the regulatory systems being uncovered are specific, but there is also considerable “cross-talk” between different circuits. Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria is a comprehensive two-volume work bringing together both review and original research articles on key topics in stress and environmental control of gene expression in bacteria. Volume One contains key overview chapters, as well as content on one/two/three component regulatory systems and stress responses, sigma factors and stress responses, small non-coding RNAs and stress responses, toxin-antitoxin systems and stress responses, stringent response to stress, responses to UV irradiation, SOS and double stranded systems repair systems and stress, adaptation to both oxidative and osmotic stress, and desiccation tolerance and drought stress. Volume Two covers heat shock responses, chaperonins and stress, cold shock responses, adaptation to acid stress, nitrosative stress, and envelope stress, as well as iron homeostasis, metal resistance, quorum sensing, chemotaxis and biofilm formation, and viable but not culturable (VBNC) cells. Covering the full breadth of current stress and environmental control of gene expression studies and expanding it towards future advances in the field, these two volumes are a one-stop reference for (non) medical molecular geneticists interested in gene regulation under stress.

The second edition of Bacterial Stress Responses incorporates and reviews the vast number of new findings that have greatly advanced the understanding of bacterial stress responses in the decade since the publication of the first edition. Readers will discover how this improved understanding not only enhances our knowledge of all cellular regulation at the molecular level, but also provides new ammunition in the fight against pathogens and helps optimize the use of bacteria in biotechnology.

Microorganisms are essential for the production of many foods, including cheese, yoghurt, and bread, but they can also cause spoilage and diseases. Quantitative Microbiology of Food Processing: Modeling the Microbial Ecology explores the effects of food processing techniques on these microorganisms, the microbial ecology of food, and the surrounding issues concerning contemporary food safety and stability. Whilst literature has been written on these separate topics, this book seamlessly integrates all these concepts in a unique and comprehensive guide. Each chapter includes background information regarding a specific unit operation, discussion of quantitative aspects, and examples of food processes in which the unit operation plays a major role in microbial safety. This is the perfect text for those seeking to understand the quantitative effects of unit operations and beyond on the fate of foodborne microorganisms in different foods. Quantitative Microbiology of Food Processing is an invaluable resource for students, scientists, and professionals of both food engineering and food microbiology.