With this project, which requires the synchrotron light, we intend to study precisely the phenotypic variability (membrane fluidity) of a subset of species from Saccharomycotina, some Debaryomyces, which are of high interest for food biotechnology and produce omega 3 fatty acids. We hypothesize that contrasted omega 3 fatty acid content lead to specific physiological properties like contrasted membrane fluidity. To confirm our model we need DUV DISCO beamline to perform measurement of fluorescence anisotropy.