Microbial Water Stress Physiology: Principles and Perspectives

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Microbial Water Stress Physiology Principles and Perspectives A. D. Brown Department of Biology, University of Wollongong, Australia. The book is concerned with the physiological factors that enable microorganisms to tolerate chronic stress, that is to thrive at low levels of water potential, whether generated by high salinities, high concentrations of non-electrolytes or by low matric potential, and to survive acute stress by adapting to changes in water potential. The thermodynamic principles that underly these physiological responses are examined, as are representative types of natural habitat capable of causing water stress. A chapter is given to the extreme halophils, the Halobacteriaceae, with emphasis on the interactions of protein and lipid chemistry, dissolved salts and water structure. Other chronic stress responses are examined in a range of eu- and prokaryotic microorganisms with emphasis on biochemical as well as physiological requirements. Turgor/volume control is discussed theoretically and empirically in relation to the use of inorganic ions and organic metabolites for the purpose. Prevailing notions of regulating either turgor or volume are challenged. Turgor/volume control with metabolites is treated as a particular example of metabolic regulation and is examined with emphasis on effects of protein concentration. The protective action of compatible solutes is discussed and a prevailing view that these compounds function by stabilizing protein structure is challenged.