2.4.6. Emulsification indexEmulsifying index was determined according to Cooper andGoldenberg [21]. Briefly, 2 mL of cell-free supernatant were addedto 2 mL hydrophobic source, and the mixture was vortexed for2 min. After 24 h, the height of emulsion layer was measured. Theemulsification index (EI24) was calculated using the height of theemulsion layer and the height of total solution [21]. The emulsify-ing capacity of the crude biosurfactant in forming stable emulsionswas evaluated using motor oil SAE 15W-40 (Texaco) and soybeanoil (Bunge).