Adaptational changes in Staphylococcus aureus MF 31 grown above its maximum growth temperature when protected by sodium chloride: lipid studies

Abstract

Staphylococcus aureus MF31 was grown to stationary phase in a complex medium at 30, 37, and 43 °C in the absence of salt and at 37 and 46 °C in the same medium supplemented with 1 M NaCl. The principal phospholipids were cardiolipin, phos-phatidylglycerol, aminoacylphosphatidyl glycerol, mono- and di-glycosyldiglyceride, and traces of phosphoglycolipid. The proportion of cardiolipin decreased with increasing growth temperature, but only slightly in the presence of 1 M NaCl, while that of aminoacylphosphatidyl glycerol was unaffected by growth temperature in absence of salt, but was about halved in the presence of 1 M NaCl. The net negative charge per mole phospholipid was greatly increased in the presence of 1 M NaCl. In the absence of salt, temperature had no effect on the total lipid content, but cells from the 46 °C culture in 1 M NaCl contained 25% less total lipid. The proportion of phospholipid in the total lipids, both in the absence and presence of salt, declined with increasing growth temperature. The proportion of glycolipids, however, increased with temperature both in the absence and presence of salt. It is suggested that the increase in glycolipid content and in negative charge/mole phospholipid is a part of the adaptation of S. aureus to the combination of high temperature and 1 M NaCl giving its membrane increased stability and possibly helping to exclude Cl− anion from the cell interior.