Primary recovery of thermostable lipase 42 derived from recombinant Escherichia coli BL21 in aqueous two-phase flotation

摘要

An aqueous two-phase flotation (ATPF) composed of polyethylene glycol (PEG) and sodium citrate was constructed for direct purification of thermostable lipase 42 from recombinant Escherichia coli BL21(DE3) pLysS. The influences of varying phase forming composition, tie-line length (TLL), volume ratio (V_R), crude loading (C_L), system pH, gas nitrogen flow rate (F_R) and flotation time (F_t) upon ATPF partitioning performance were investigated. The optimum purification condition of lipase was achieved at PEG 8000/ sodium citrate ATPF comprising TLL of 25.4, V_R of 0.3, C_L of 20% (w/w) at pH 7 with average F_t of 10 min and F_R at 20 mL/min. Lipase was successfully purified using ATPF up to 4.05-fold with a separation efficiency of 99%. Result of this study also demonstrated that recovery yield of lipase in PEG phase of up to 96% was achieved. These results reveal the potential of ATPF partitioning in recovery and purification of recombinant lipase.