Adapting to Changing Salinities: Biochemistry, Genetics, and Regulation in the Moderately Halophilic Bacterium Halobacillus halophilus
The availability of water is the most important prerequisite for life of any living cell and exposure of cells to hypersaline conditions always threatens the cells with a drastic loss of water followed by shrinkage and cell death if no counter measures are taken. To re-establish the essential turgor pressure, cells increase the water activity of their cytoplasm using one of two principal strategies: the “salt-in-cytoplasm” and the “compatible solute” strategy. The former describes the accumulation of inorganic ions, mainly K+ and Cl−, in the cytoplasm, until the internal salt concentration is similar to the extracellular one. This strategy can be found in extremely halophilic Halobacteria (Archaea) and halophilic, anaerobic Haloanaerobiales (Bacteria) and Salinibacter ruber. This strategy is not covered here but the reader is referred to excellent reviews (Galinski and Trüper 1994; Ventosa et al. 1998). The vast majority of bacteria cope with increasing osmolality by...
KeywordsGlutamine Synthetase Compatible Solute Glycine Betaine Glutamine Synthetase Activity External Salinity
Work from the author’s laboratory is supported by the Deutsche Forschungsgemeinschaft.
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