Optimization and characterization of biosurfactant production by Bacillus subtilis isolates towards Microbial Enhanced Oil Recovery applications

摘要

Biosurfactant production by three Bacillus subtilis strains (#309, #311 and #573) isolatedfrom Brazilian crude oils was optimized based on different carbon and nitrogen sources. The lowestsurface tension values were obtained using sucrose containing media for the three isolates.Biosurfactants produced by each strain were characterized by Fourier transform infrared spectroscopy(FTIR), proton nuclear magnetic resonance (1HNMR), and Matrix-assisted laser desorption ionizationtimeof flight mass spectrometry (MALDI-TOF). The chemical characterization showed that the threeisolates produced very similar mixtures, containing C13-, C14- and C15-surfactin, although in differentproportions. The structure of surfactins produced by the three strains was shown to be in goodagreement with their surface-activities. The interfacial-activities of the biosurfactants werecharacterized and compared with chemical surfactants. Furthermore, the application of biosurfactantsand chemical surfactants in oil recovery was evaluated. The results obtained showed thatbiosurfactants have better interfacial-activity and oil recovery efficiency than common chemicalsurfactants, thus being more attractive to be applied in Microbial Enhanced Oil Recovery.