||"Ocean water contains ˜500mM Na+, whereas the internal sodium concentration of growing marine bacteria may be more than an order of magnitude lower (Speelmans et al. 1995). Brown (1990 and refs. therein) has shown that compatible solutes, including potassium, play an important role in maintaining the turgor pressure in many bacteria. If bacterial growth is carbon limited, as may occur in the sea (Currie and Kalff 1984), compatible organic solutes are less likely to be used for osmotic purposes. Other important ions in sea water are potassium (˜10mM), magnesium (˜50 mM), sulfate (˜50mM), calcium (˜10mM), and chloride (˜560mM). Among these, the potassium concentration of G- bacteria has been reported to be greater than 50 mM in growing cells, while G+ bacteria have cellular concentrations up to 500 mM (Harder and Dijkhuizen 1983)."