Baccile, NikiNikiBaccileSelmane, MohamedMohamedSelmaneGriel, Patrick lePatrick leGrielPrévost, SylvainSylvainPrévostPerez, JavierJavierPerezStevens, Christian V.Christian V.StevensDelbeke, ElisabethElisabethDelbekeZibek, SusanneSusanneZibekGuenther, MichaelMichaelGuentherSoetaert, WimWimSoetaertBogaert, Inge N.A. vanInge N.A. vanBogaertRoelants, SophieSophieRoelants2022-03-052022-03-052016https://publica.fraunhofer.de/handle/publica/24518110.1021/acs.langmuir.6b00488Microbial glycolipids are a class of well-known compounds, but their self-assembly behavior is still not well understood. While the free carboxylic acid end group makes some of them interesting stimuli-responsive compounds, the sugar hydrophilic group and the nature of the fatty acid chain make the understanding of their self-assembly behavior in water not easy and highly unpredictable. Using cryo-transmission electron microscopy (cryo-TEM) and both pH-dependent in situ and ex situ small angle X-ray scattering (SAXS), we demonstrate that the aqueous self-assembly at room temperature (RT) of a family of v-d-glucose microbial glycolipids bearing a saturated and monounsaturated C18 fatty acid chain cannot be explained on the simple basis of the well-known packing parameter. Using the ""pH-jump"" process, we find that the molecules bearing a monosaturated fatty acid forms vesicles below pH 6.2, as expected, but the derivative with a saturated fatty acid forms infinite bilayer sheets below pH 7.8, instead of vesicles. We show that this behavior can be explained on the different bilayer membrane elasticity as a function of temperature. Membranes are either flexible or stiff for experiments performed at a temperature respectively above or below the typical melting point, TM, of the lipidic part of each compound. Finally, we also show that the disaccharide-containing acidic cellobioselipid forms a majority of chiral fibers, instead of the expected micelles.en541journal article