Two Bacillus strains capable of emulsifying immiscible organophosphorus pesticides were isolated by enrichment methods. The emulsifying factor produced by Bacillus strain FE-2 has a high molecular weight, is Iysozyme sensitive and thermostable, and can be precipitated with trichloroacetic acid or ammonium sulfate; it may be a glycolipopeptide. It is specific for immiscible organophosphorus pesticides and is secreted during growth in the presence of such pesticides.