Partial purification of crude lipase extract from Yarrowia lipolytica: Precipitation, aqueous two-phase systems (ATPS), and immobilization methods

Efforts have been concentrated on developing alternative methods of enzyme purification that are less costly and highly efficient. In this work, we evaluated three different methods for lipase purification from Yarrowia lipolytica, such as precipitation using ammonium sulfate, ethanol, or acetone; aqueous two-phase systems (ATPS) based on polyethylene glycol (PEG) and potassium phosphate; and direct immobilization. It was impossible to obtain stable precipitates of the enzyme due to the low concentration of total protein and the presence of biosurfactant produced by the microorganism. Different mixture compositions were selected for the partitioning study. Three ATPS showed selective partitioning of the target enzymes, i.e., lipase and protease migrated to opposite phases. In the ATPS composed of 13 wt% PEG-4000 and 10 wt% salts, it was possible to achieve a purification factor for lipase of 4.2. Purification by immobilization performed by lipase-lipase interactions showed three lipases of distinct sizes in the crude extract. In the immobilization method by hydrophobic supports, phenyl-agarose and butyl‑agarose were more selective in immobilizing than octyl-agarose. In the ion exchange immobilization method, only the lipases identified at 66 kDa and 41 kDa have an attraction for DEAE-agarose (anionic) and sulfopropyl-agarose (cationic) matrices.