Recovery of Mannosylerythritol Lipids Using Alcohol/Salt Aqueous Two-Phase Extraction

Mannosylerythritol lipids (MELs) are biosurfactants with applications in cosmetics, pharmaceuticals, and bioremediation. However, large-scale production using oil substrates complicates downstream recovery, resulting in low yields and high production costs. This study investigates aqueous two-phase extraction (ATPE) as an alternative recovery method. Alcohol/salt aqueous two-phase systems (ATPS) were evaluated using ethanol, 1-propanol, and 2-propanol in combination with various anions (phosphate, sulfate, citrate, and tartrate), while varying pH, temperature, and salt concentrations. The 1-propanol/sulfate system achieved the highest MEL recovery of 83.4% in the alcohol-rich top phase. The addition of 2% (w/w) NaCl improved recovery to 86.4%, while 8% (w/w) NaCl decreased MEL recovery. Since U. maydis coproduces cellobiose lipids (CBLs), we demonstrate that an ethanol/tartrate system could effectively separate MELs from CBLs. Oleic acid, a key contaminant, was found to preferentially partition into the top phase, indicating the necessity for further purification. To validate the system, MELs produced by Ustilago maydis were recovered using the 1-propanol/sulfate ATPS, yielding 87.28% recovery. This study is the first to demonstrate ATPE for MEL recovery and separation from coproducts such as CBLs, offering a promising and scalable alternative to conventional purification methods in industrial biosurfactant production.