Modulation in membrane lipids of Escherichia coli and Staphylococcus aureus in response to varying NaCl concentrations

Abstract

The effect of varying NaCl concentrations on membrane lipids of Escherichia coli and Staphylococcus aureus cultivated at 37°C was studied. Lipid profiles of the membrane extracts were resolved by thin layer chromatography (TLC) using polar and neutral lipids solvent systems, with their fatty acid constituents determined via gas chromatography-mass spectrometry (GC-MS). Polar lipids identified were cardiolipin, phosphatidic acid, phosphatidylglycerol, phosphatidylethanolamine and lysophosphati-dylglycerol, while neutral lipids for both microorganisms were steryl-esters, triacylglycerols, diacylglycerols and monoacylglycerols at the different NaCl concentrations of growth however triacylglycerol was not detected in S. aureus at 3% NaCl. Fatty acids for E. coli were C15:0, C16:0 and C18:1 at 0% NaCl but C16:2 was also detected at 3% NaCl. S. aureus fatty acids were C13:0, C14:0, C16:0 and C18:1 for 0% NaCl while at 3% NaCl, additional fatty acids observed include C12:0, C15:0 and C16:1. The lipids expressed were relatively similar; however, their fatty acids differed in constituents and abundance.   Key words: NaCl concentration, lipid profiles, fatty acids, membranes, Escherichia coli, Staphylococcus aureus.