| The immobilized cross-linked enzyme aggregates (CLEAs-L) on magnetic rosin-based polymer were prepared. The effects of preparation conditions on the activity of immobilized CLEAs-L were evaluated. Moreover, the properties and structures of immobilized CLEAs-L were investigated. The results showed that the optimal preparation conditions were obtained as follows: dosage of precipitant (absolute ethanol) 30%, lipase mass concentration 4 g/L, glutaraldehyde dosage 0.3% in the first cross-linking reaction, reaction time 2 h, glutaraldehyde dosage 1% in the second cross-linking reaction, and the mass ratio of CLEAs-L to carrier 2.5∶?1. Under these conditions, the recovery rate of enzyme activity was 86.52%, and the optimal temperature and pH of immobilized CLEAs-L were 45 ?℃ and 7.0 respectively. The thermal and storage stability of immobilized CLEAs-L were improved remarkably compared with the free lipase and CLEAs-L. After six batch reactions, the recovery rate of enzyme activity of immobilized CLEAs-L was still above 60.00%. |
