High osmolarity in hypersaline conditions can be deleterious to cells since water is lost to the external medium until osmotic equilibrium is achieved. To prevent of cellular water under these circumstances, halophiles generally accumulate high solute concentration within the cytoplasm (Galinski, 1993).When an isoosmotic balance with the medium is achieved, cell volume is maintained. The compatible solutes os molytes that accumulate in halophlies are usually amino acids and polyoils, e.g. glycine betaine, ectoine, sucrose, thehalose and glycerol, which do not disrupt metabolic processes and have no net charge at physiological pH. A major exception is for the halobacteria and some other extreme halophiles, which accumulate KCl equal to the external concentration of NaCl. Halotolerant yeasts and green algae accumulate polyoils, while many halophilic and halotolerant bacteria accumulate glycine betaine and ectoine. Compatible solute accumulation may occur by biosynthesis, de novo or from storage material, or by uptake from the medium.