IJSRP, Volume 5, Issue 5, May 2015 Edition [ISSN 2250-3153]
Arpita Dey, Tushar Kanti Maiti and Pranab Roy
Extracellular lipase producing psychrotrophic Pseudomonas ADT3 (NCBI GenBank Acc.no.JX914667) isolated from soil sample of Ny- Alesund, Svalbard, Arctic region produced maximal lipase activity of 527.8U/mg after 48 hours at pH 8.5 and temperature 22°C in presence of 1.2mM lead as cofactor. It was partially purified 2.9 folds by ammonium sulphate precipitation (80%). Enzymatic performance was improved by immobilization of enzyme on various carriers viz. Alginate and polyacrylamide gel. The immobilization yield of enzyme immobilized in polyacrylamide gel was low (40.0%) in comparison to that immobilized with alginate (70.0%). Different concentrations of alginate and calcium chloride were studied to acquire stable beads. Optimum concentration of alginate and calcium chloride was 2% and 0.12M respectively. The immobilized enzyme was found to be stable in alkaline pH. The maximal activity for immobilized enzyme was found at pH 8.5. Broader pH tolerance could be achieved by immobilization. Temperature optima of the enzyme showed no changes before and after immobilization i.e. 22°C. But the thermal stability was enhanced after immobilization. Immobilized enzyme remained active up to 50 °C while the activity of the free enzyme started to decrease from 40 °C. Even at 70°C immobilized enzyme retained 25% of residual activity but free enzyme totally loses enzyme activity. The storage stability of entrapped lipase up to 50% was found after 5 days at 4°C, while at 30°C the enzyme lost 60% of its activity after 2 days. The enzyme can be reused up to 5 cycles which is a promising technique for large-scale preparation of immobilized lipase for industrial applications.