Linear heptapeptide surfactin was prepared by alkaline cleavage of the lactone ring of cyclic surfactin. The structure of linear surfactin was characterised and confirmed by FAB-mass-spectroscopy, FT-IR and HPLC analysis. It was found that linear surfactin easily forms micelles in aqueous solutions by coordinating beta-sheet formation from alpha-helical monomolecules, and the cmc value found to be 1.28x10(5) M. The CD spectra indicates conformational change of linear surfactin from alpha-helical below cme to beta-sheet above cmc.