Microbiological Reviews · 1989 · 715 citations · 0 references
Life SciencesMicrobiologyPhysiologyMicrobial GeneticsMicrobial PhysiologyStress PhysiologyBacterial Gene RegulationBacterial MetabolismBacterial PhysiologyBacterial SurvivalMicrobial HomeostasisMicrobial Stress Response SystemsBacterial Adaptation To Environmental StressBacterial OsmoregulationOsmotic GradientOsmotic StressOsmotic Stress ResponseOsmotic Stress ToleranceOsmotic TransportTurgor Pressure
Bacterial survival across habitats depends on osmotic stress responses, primarily the accumulation of solutes such as K⁺, glutamate, trehalose, proline, and glycine betaine to maintain cytoplasmic osmolarity and turgor pressure. This review surveys the mechanisms by which bacteria adapt to osmotic changes.
The capacity of organisms to respond to fluctuations in their osmotic environments is an important physiological process that determines their abilities to thrive in a variety of habitats. The primary response of bacteria to exposure to a high osmotic environment is the accumulation of certain solutes, K+, glutamate, trehalose, proline, and glycinebetaine, at concentrations that are proportional to the osmolarity of the medium. The supposed function of these solutes is to maintain the osmolarity of the cytoplasm at a value greater than the osmolarity of the medium and thus provide turgor pressure within the cells. Accumulation of these metabolites is accomplished by de novo synthesis or by uptake from the medium. Production of proteins that mediate accumulation or uptake of these metabolites is under osmotic control. This review is an account of the processes that mediate adaptation of bacteria to changes in their osmotic environment.