[Objective] The purpose of this research was to filter a high yield strain of biosurfactant and optimize its fermentation conditions.[Method]One biosurfactant-producing microorganism E was isolated from samples collected from polluted water with the methods of blood-plate and oil-plate.Based on the results of morphology,physiological and biochemical properties and phylogenetic analysis of 16S rDNA sequence,strain E was identified as Proteus mirabilis E.The medium composition and the cultivation conditions w...