Demulsification efficiency and the active component of a bacterial strain

A full-culture solution of the strain XH-1 belonging to Bacillus mojavensis isolated from contaminated oily soil in Daqing oilfield was used to demulsify the O/W model emulsion made by Tween 60, Span 60 and kerosene. The effects of cultural and demulsification conditions on the demulsification rate of XH-1were investigated. The results indicated that 85% of demulsification rate was achieved after 24 h demulsification of the strain. The demulsification performance of XH-1 was better than those of chemical demulsifiers in the laboratory experiment. The strain XH-1 also showed a stable heredity for biodemulsifier production. The optimal cultural and demulsification conditions were followings: the mixture of glucose and liquid paraffin as carbon source, pH=6.5 and rotating rate of 140-160 r/min. The strain did not possess thermostability, but cool-resistance. The ultrasonic treatment of XH-1 had little effect on its demulsification performance, however, its demulsification activity was inhibited by the pepsin, trypsin and urea treatments. It is deduced through the microscope observation and analysis that the demulsification active component of the strain XH-1 was the extracellular secreted protein substances.