| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 87 === In this present thesis, the recovery of alkaline lipase from Acinetobacter radiaresistens by adsorption was investigated. It was found that the hydrophobic adsorbent of Accurrel MP1000 would not effectively adsorb enzyme under the conditions of weak ionic strength. With Celite 535 as the adsorbent, the concentration and pH of the phosphate buffer might effect the enzyme adsorption. However, the further addition of salts to the phosphate buffer would not improve the enzyme recovery due to the existing ions in the solution. Adding salts to RO water enhance the enzyme adsorption, in which 100 mM (NH4)Cl was found to give the highest lipase activity and protein recovery with 1.65-fold purification.
The surface charge of Celite 535 in RO water was found to be negative from the zeta potential measurement. Although salts did effect the zeta potential of Celite 535, no correspondence between the changes of zeta potential and enzyme adsorption was observed. This implied that electrostatic interaction force between Celite 535 and lipase was not the predominate factor during the protein adsorption.
Compared to the adsorption, a higher overall protein recovery without purification effects was found when using the precipitation method of adding acetone into the aqueous solution. With the acetone volume percentage higher than 52.4 %, more than 85 % recovery of lipase activity and protein were obtained. Moreover, adding Celite 535 to the precipitation solution would not improve the recovery such that the adsorb just acted as a dispersant and filler.
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