Formation of supported lipid bilayers of Escherichia coli extracted lipids and their surface morphologies

As a bacterial model cell system, a reconstituted Escherichia coli (E. coli) cell membrane has been studied. The chemically extracted E. coli lipid mixture such as polar lipid extract (PLE) is widely used in the previous studies. These lipid extracts contain three main phospholipid classes, phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and cardiolipin (CA). These lipids have different electrical and physical properties. However, the characters of the lipid bilayer membrane composed of each component have not been investigated. Understanding the behaviors of each lipid extract component leads to fabricating bacterial model membrane platforms, and to further understanding of roles of lipids in bacterial membrane reactions. In this study, we examined supported lipid bilayers of E. coli extracted PE, PG and CA on thermally oxidized SiO2/Si and mica substrates with fluorescence microscopy and atomic force microscopy.