Extraction of lipase from Rhizopus microsporus fermentation culture by aqueous two-phase partitioning

The purification of a desired protein from the complex mixture of biomolecules in a fermentation broth is one of the main challenges in industrial-scale biotechnological processes. For partial purification of industrial enzymes, one possible approach is to use aqueous two-phase extraction (APTE) as a primary downstream processing step. In the present study, the feasibility of utilizing ATPE for the purification of lipase from Rhizopus microsporus fermentation culture was investigated. The effects of the phase composition and salt type, molecular weight of the polyethylene glycol (PEG), pH of the system, sample loading and addition of neutral salts on lipase partitioning were investigated at 24 °C. In most of the examined aqueous two-phase systems (ATPSs), lipase showed affinity to the top phase. Optimum conditions for lipase purification were obtained in 20% PEG 2000/12% (NH4)2SO4, with 5% Na2CO3 addition at pH = 8 for 30% crude load. For the optimized ATPS, the recovery yield and purification factor in t...