(520e) Rhamnolipid Production and Application in Microbial Enhanced Oil Recovery from Metabolically Engineered Bacteria

Rhamnolipids as potent natural biosurfactant have wide potential biotechnological applications such as enhancing oil recovery, biodegradation and bioremediation. Rhamnolipids were composed of rhamnose sugar molecules and ß-hydroxyalkanoic acids. Based on the methodology of metabolic engineering as well as directed evolution, several bacteria, including Escherichia coli, Pseudomonas aeruginosa, and P. fluorenscens, were engineered to produce different types of rhamnolipids, including mono-rhamnolipid and di-rhamnolipid. Surfactant performance of rhamnolipid from engineered strains was evaluated by LC/MS, interfacial tension (IFT) and oil recovery via core flooding. IFT analysis revealed that pH and salt concentration in the buffer would significantly affect the properties of rhamnolipid in interfacial performance. LC/MS analysis showed a relationship between the chemical structure of rhamnolipid and IFT. At low concentration of engineered rhamnolipid, more than 40% of the remaining oil could be recovered in a sand pack flow test. These results were therefore important for considering the exploration of the studied rhamnolipid as an enhanced oil recovery agent.