Starvation in Bacteria


Book Description

Concerted efforts to study starvation and survival of nondifferentiating vegeta tive heterotrophic bacteria have been made with various degrees of intensity, in different bacteria and contexts, over more than the last 30 years. As with bacterial growth in natural ecosystem conditions, these research efforts have been intermittent, with rather long periods of limited or no production in between. While several important and well-received reviews and proceedings on the topic of this monograph have been published during the last three to four decades, the last few years have seen a marked increase in reviews on starvation survival in non-spore-forming bacteria. This increase reflects a realization that the biology of bacteria in natural conditions is generally not that of logarithmic growth and that we have very limited information on the physiology of the energy-and nutrient-limited phases of the life cyde of the bacterial cello The growing interest in nongrowing bacteria also sterns from the more recent advances on the molecular basis of the starvation-induced nongrowing bacterial cello The identification of starvation-specific gene and protein re sponders in Escherichia coli as weIl as other bacterial species has provided molecular handles for our attempts to decipher the "differentiation-like" responses and programs that nondifferentiating bacteria exhibit on nutrient limited growth arrest. Severallaboratories have contributed greatly to the progress made in life after-log research.




Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria


Book Description

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.




Lost in Starvation


Book Description

Heterotrophic marine bacteria navigate a heterogeneous landscape of resources. Bacterial populations cycle through periods of feasting when attached to nutrient particles and periods of famine when foraging between hotspots; thus, bacterial physiological states and ecological processes are intertwined. The stress response to nutrient limitation appears within three hours, while the encounter time to new particles has been estimated to happen on the scale of days. Therefore, it is unclear how the phenotypic changes undergone by bacteria during starvation affect their ability to search for and acquire nutrients. Here, we quantified the physiological responses of the marine heterotroph Vibrio coralliilyticus to carbon and nitrogen starvation and its subsequent success at foraging in a landscape of resource particles. We compare the foraging success of different bacterial populations in terms of the minimum number of particles needed for ten percent of such a population to encounter any particle. We parametrize a model of bacterial foraging during starvation superposing multiple Poisson processes using measurements of viability, motility, attachment, and renewed growth observed for Vibrio coralliilyticus over several days of carbon and nitrogen limitation. We find that motility loss, bacterial persistence, and reductive cellular division are key behaviours determining foraging success. While motility loss increases the number of particles required for successful foraging in a population, bacterial persistence relaxes that constraint. Heightened reductive division accelerates the speed at which the first ten percent of the initial bacterial population achieves a particle encounter. This work provides a quantitative estimate of the influence of nutrient-limited phenotypes on bacterial foraging success in a marine environment.




Biology of Starvation in Humans and Other Organisms


Book Description

This important book examines the biology of starvation in humans and other organisms. Topics discussed herein include the physiological landscape of the stationary phase and the molecular events that allow the Mycobacterium smegmatis species to survive prolonged periods of starvation; the biochemical aspects of starvation in yeasts; the epidemiology of hunger in the world and the hunger-obesity paradox; starvation of bacteria for amino acids as an example of prokaryotic response to nutritional deprivation; intra-uterine growth retardation due to maternal undernutrition; and the physiological changes during starvation in fish.




Bacterial Responses to Modeled Reduced Gravity Conditions


Book Description

Relatively few studies have examined bacterial responses to the reduced gravity (RG) conditions that are experienced by bacteria grown in orbit in space vessels, such as International Space Station. Because of limited access to space conditions, clinorotation is utilized to model certain aspects of RG conditions such as lack of sedimentation, low shear, and low turbulence (here referred to as modeled reduced gravity [MRG] conditions). RG conditions, either actual or modeled, alter a wide variety of bacterial parameters such as growth, resistance to multiple stresses, and virulence. While, a few studies have speculated that conditions of MRG act as a direct signal thus eliciting some of these bacterial responses, some studies have speculated that extra-cellular changes (such as accumulation of toxic by-products and/or reduced availability of nutrients) that are indirectly altered by these conditions might account for the changes in bacterial behavior. The overarching hypothesis for this study is that bacterial responses to MRG conditions vary with availability of nutrients that are indirectly altered by these environmental conditions. Observations made to test the hypothesis were based on changes in expression of whole genome and of specific genes in Escherichia coli grown under MRG as compared to normal gravity (NG) controls. In addition, E. coli and Staphylococcus aureus starvation-related physiological responses were examined under nutrient-rich and -poor conditions and at both exponential and stationary phases of growth. E. coli whole genome expression patterns revealed the simultaneous expression of starvation inducible genes and genes associated with multiple stress responses. Subsequent gene expression studies showed that increased expression of multiple stress response genes under MRG occurs only during the latter stages of growth in rich medium and resembles the general stress response. Examination of E. coli and S. aureus physiology suggested that bacteria become physiologically more active and more viable under MRG conditions as compared to NG conditions, however, these responses vary with growth media and growth phase. Overall, my data suggests that bacterial responses to MRG are due to changes in the microenvironment around the bacteria, such as reduced availability of nutrients, that are indirectly altered, rather than by direct gravitational effects.




Bacterial Physiology


Book Description

Bacterial Physiology focuses on the physiology and chemistry of microorganisms and the value of bacterial physiology in the other fields of biology. The selection first underscores the chemistry and structure of bacterial cells, including the chemical composition of cells, direct and indirect methods of cytology, vegetative multiplication, spores of bacteria, and cell structure. The text then elaborates on inheritance, variation, and adaptation and growth of bacteria. The publication reviews the physical and chemical factors affecting growth and death. Topics include hydrogen ion concentration and osmotic pressure; surface and other forces determining the distribution of bacteria in their environment; dynamics of disinfection and bacteriostasis; bacterial resistance; and types of antibacterial agents. The text also ponders on the anaerobic dissimilation of carbohydrates, bacterial oxidations, and autotrophic assimilation of carbon dioxide. The selection is a dependable reference for readers interested in bacterial physiology.




Bacterial Stress Responses


Book Description

Gain new insight on utilizing bacterial stress responses to better combat bacterial infection with antibiotics and improve biotechnology. • Reviews the vast number of new findings that have greatly advanced the understanding of bacterial stress responses in the past 10 years. • Explores general regulatory principles, including the latest findings from genomics studies, including new research findings on both specific and general stress responses. • Details how stress responses affect the interactions between bacteria and host cells and covers bacterial stress responses in different niches and communities, with an emphasis on extreme environments.




Fire Blight


Book Description

Addresses the bacterial disease, fire blight, and includes its epidemiology, distribution, host range, detection and infection. This work also considers the pathogen, including its biochemistry, genetics and pathogenicity, and finally reviews control, including biological methods.




Stress Responses of Lactic Acid Bacteria


Book Description

Beginning with the basics of lactic acid bacteria and stress response, then working into specific fields of research and current developments, Stress Responses of Lactic Acid Bacteria will serve as an essential guidebook to researchers in the field, industry professionals, and advanced students in the area. The exploration of stress responses in lactic acid bacteria began in the early 90s and revealed the differences that exist between LAB and the classical model microorganisms. A considerable amount of work has been performed on the main genera / species of LAB regarding the genes implicated and their actual role and regulation, and the mechanisms of stress resistance have also been elucidated. Recent genome and transcriptome analyses complement the proteome and genetic information available today and shed a new light on the perception of and the responses to stress by lactic acid bacteria.