Immobilization and stabilization of Pseudomonas aeruginosa SRT9 lipase on tri(4-formyl phenoxy) cyanurate

다국어 초록 (Multilingual Abstract)

Lipase was extracted and purified from Pseudomonas aeruginosa SRT9. Culture conditions were optimized and highest lipase production amounting to 147.36 U/ml was obtained after 20 h incubation. The extracellular lipase was purified on Mono QHR5/5 column, resulting in a purification factor of 98-fold with specific activity of 12307.81U/mg. Lipase was immobilized on tri (4-formyl phenoxy) cyanurate to form Schiff’s base. An immobilization yield of 85% was obtained. The native and immobilized lipases were used for catalyzing the hydrolysis of olive oil in aqueous medium. Comparative study revealed that immobilized lipase exhibited a shift in optimal pH from 6.9 (free lipase) to 7.5 and shift in optimal temperature from 55℃ to 70℃. The immobilized lipase showed 20-25% increase in thermal stability and retained 75% of its initial activity after 7 cycles. It showed good stability in organic solvents especially in 30% acetone and methanol. Enzyme activity was decreased by ~60% when incubated with 30% butanol. The kinetic studies revealed increase in K_M value from 0.043mM (native) to 0.10 mM for immobilized lipase. It showed decrease in the V_max of immobilized enzyme (142.8 μmol min^(−1) mg^(−1)), suggesting enzyme activity decrease in the course of covalent binding. The immobilized lipase retained its initial activity for more than 30 days when stored at 4 ℃ in Tris-HCl buffer pH 7.0 without any significant loss in enzyme activity.

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