BIOEMULSIFIER PRODUCTION BY BACILLUS-STEAROTHERMOPHILUS VR-8 ISOLATE

Bacillus stearothermophilus produced an extracellular bioemulsifier during growth in a medium containing 4% crude oil. Over the temperature range of 45 degrees to 70 degrees C, maximum recovery (0.6 g 1(-1)) occurred at 50 degrees C. The emulsifier had its greatest activity on benzene, among the hydrocarbons tested. Acetone precipitated, dialysed emulsifier contained 46% protein, 16% carbohydrate and 10% lipid. The emulsification activity was stable over a broad range of temperature (50-80 degrees C), pH (2-8) and salt concentration (5% NaCl, 5% CaCl2 and 1% MgCl2). Thus, this emulsifier was found to be better than liposan (showing emulsifying activity between pH 2-5 and stable up to 70 degrees C) in terms of pH and temperature stability. Additionally, it was also salt tolerant, suggesting its potential use in crude oil tank clean-up and enhanced oil recovery.