STABILITY OF PRESSURE EXTRUDED LIPOSOMES MADE FROM ARCHAEBACTERIAL ETHER LIPIDS

Ether lipids were obtained from a wide range of archaeobacteria grown at extremes of pH, temperature, and salt concentration. With the excep tion of Sulfolobus acidocaldarius, unilamellar and/or multilamellar li posomes could be prepared from emulsions of total polar lipid extracts by pressure extrusion through filters of various pore sizes. Dynamic light scattering, and electron microscopy revealed homogeneous liposom e populations with sizes varying from 40 to 230 nm, depending on both the lipid source and the pore size of the filters. Leakage rates of en trapped fluorescent or radioactive compounds established that those ar chaeobacterial liposomes that contained tetraether lipids were the mos t stable to high temperatures, alkaline pH, and serum proteins. Most e ther liposomes were stable to phospholipase A(2), phospholipase B and pancreatic lipase. These properties of archaeobacterial liposomes make them attractive for applications in biotechnology.