Patent ID: 8883968

Claim:
A method for producing a surfactin or a salt thereof, comprising the steps of adding an organic solvent containing a branched alkyl alcohol and an auxiliary solvent to a culture fluid containing the surfactin or the salt thereof, or to a solution obtained by removing an insoluble component from the culture fluid, and extracting the surfactin or the salt thereof with the organic solvent, wherein a total ratio of the branched alkyl alcohol and the auxiliary solvent is not less than 0.6 parts by weight and not more than 1.5 parts by weight relative to 1 part by weight of the culture fluid, and the surfactin or the salt thereof is represented by the formula (1): wherein * indicates an optically active center; X is an amino acid selected from leucine, isoleucine and valine; R is a C 9-13 linear alkyl group or a C 9-13 branched alkyl group; and M is a hydrogen, an alkali metal, an alkaline earth metal, or an optionally-substituted amine.