Many species of bacteria adapt to saline conditions by the intracellular accumulation of low-molecular-weight organic solutes called osmolytes (77). The accumulation of osmolytes is thought to counteract the dehydration effect of low water activity in the medium but not to interfere with macromolecular structure or function (292). Rhizobia utilize this mechanism of osmotic adaptation (42, 43, 292, 295, 362). In the presence of high levels of salt (up to 300 to 400 mM NaCl), the levels of intracellular free glutamate and/or K+ were greatly increased (sometimes up to sixfold in a few minutes) in cells of R. meliloti (43, 167, 189), R. fredii (118, 119, 350), Sinorhizobium fredii (307), and rhizobia from the woody legume Leucaena leucocephala (349), K+ strictly controls Mg2+ flux during osmotic shock. An osmolyte, N-acetylglutaminyl-glutamine amide, accumulates in cells of R. meliloti (292, 294, 295); the accumulation of these osmolytes is dependent on the level of osmotic stress, the growth phase of the culture, the carbon source, and the presence of osmolytes in the growth medium.
Counter Strike Carbon Cd Key Fixed
2ff7e9595c
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