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

Sivapathasekaran, C., Mukherjee, Soumen, Sen, Ramkrishna, Bhattacharya, Biyash, Samanta, Ramapati
Bioprocess and biosystems engineering 2011 v.34 no.3 pp. 339-346
bacteria, biosurfactants, culture media, desorption, infrared spectroscopy, ionization, lipopeptides, micelles, spectral analysis, ultrafiltration
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.