Single step concomitant concentration, purification and characterization of two families of lipopeptides of marine origin

The extracellular biosurfactant product secreted by a marine bacterium was concentrated and purified directly from the fermentation broth in a single step by ultrafiltration (UF) employing YM 30 kDa (UF-I) and Omega 10 kDa (UF-II) polyethersulfone membranes. The optimum operating pressure required for both membranes, UF-I and UF-II, were found to be 30 and 35 psi, respectively. The biosurfactant from the fermentation broth was recovered in higher amounts using UF-II (89%) than using UF-I (73%). An analysis of the critical micelle concentrations (CMC) of the recovered lipopeptides showed a lower CMC value of 15 mg L⁻¹ for the UF-II product, indicating higher degree of purity (83%) when compared to that of the UF-I product (78%). The ultrafiltered products were characterized using Fourier transformed infrared spectroscopy and matrix-assisted laser desorption ionization time of flight mass spectral analysis, which demonstrated the presence of two families of lipopeptides.