PhD Theses (Energy Science and Engineering)

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Studies on immobilized lipase and biosurfactant for hydrolysis and transesterification of sunflower oil
(2012) Chatterjee, Sushovan
The principal objective of this work is immobilization of lipase and application of the immobilized lipase for hydrolysis and transesterification of sunflower oil. Lipase was isolated from the culture supernatant of Pseudomonas aeruginosa PG01. A high activity (4.1+- 0.05 U/ml) in the supernatant was detected when sunflower oil (2g/l) was used as the sole substrate. A significant production of lipase in burnt oil was observed, which was about 75% of the activity obtained when sunflower oil was used as the substrate. The extracellular lipase was successfully fractionated from the culture supernatant by ammonium- sulfate fractionating method, which was further purified by DEAS- sepharose anion exchange chromatography. The specific activity of the purified lipase was increased to 2.59 fold. The molecular weight of the DEAS sepharose filtered purified pseudomonas lipase was estimated by SDS-PAGE was found to be 55 kDa. The optimum temperature and pH of the isolated lipase was 30oC and 7, respectively. The t1/2 of the lipase at 4C and pH 7 was nearly 23 months. The stability of the powdered lipase diminished steadily with the increasing temperature from 20o C to 80o C with t1/2 of 62 days and 82 min at 20o C and 80o C respectively.