Aqueous two-phase systems based on cholinium salts and tetrahydrofuran and their use for lipase purification

• Novel ATPS composed of THF and cholinium-based salts were developed.
• The phase diagram, tie-lines and critical point were determined at 298 K.
• The concentration of components and temperature of equilibrium were investigated.
• Lipase from Bacillus produced by submerged fermentation was purified 130.1 (fold).

Aqueous two-phase systems (ATPS) formed with cholinium-based ionic liquid – ILs (or salts) are a novel, low cost, and high efficient technique for the recovery of biomolecules. This study examines the formation of ATPS based on cholinium-based salts (cholinium chloride, cholinium bitartrate and cholinium dihydrogencitrate) and tetrahydrofuran (THF) for the purification of lipase from Bacillus sp. ITP-001, produced by submerged fermentation. The optimum conditions for this purification were determined to be 40 wt% of THF and 30 wt% of cholinium bitartrate at 25 °C. A purification factor of 130.1 ± 11.7 fold, a lipase yield of 90.0 ± 0.7% and a partition coefficient of enzyme for IL-rich phase (KE = 0.11 ± 0.01) and protein contaminants for THF-rich phase (KP = 1.16 ± 0.1) were achieved.