The biosurfactant was extracted from cell-free broth at 72-h grown cells by step-by-step purification of acid precipitates using adsorption chromatography. Bacterial cells were removed from surfactant-containing medium by centrifugation (10 000 rpm for 20 min). The supernatant was
subjected to acid precipitation by adding 6 N HCl to achieve a final pH of 2.0 and allowing the precipitate to form at 4 ํC.The precipitate was pelleted at 10 000 rpm for 20 min, redissolved in distilled water, adjusted to pH 7.0, freezedried, and weighed. The dried surfactant was extracted with acetone and dried with the aid of a rotary evaporator under vacuum