The detailed functional characterization of an outer membrane for C. glutamicum is a major challenge for the future since it raises several questions regarding the resistance of the cell towards environmental stress as well as molecular traffic across the cell envelope. In spite of several structural and functional studies, many questions remain still unanswered. In this frame we propose to use OSIRIS to compare the relaxational and vibrational properties of liposomes made of dimycolate and monomycolate of trehalose from C. glutamicum and liposomes made of classical E. coli lipids, this latter taken as a reference. From the measured spectra mean square displacements and relaxation rates will be extracted. The low energy excitation spectra of the different compositions will be compared and will provide insight into the vibrational behavior and flexibility of the membranes.