Cross-linked lipase from germinating mustard (Brassica juncea) seeds : characterization and preliminary investigation of its use in the production of biodiesel from Jatropha curcas seed oil

Date

4-2009

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagros M. Peralta

Abstract

Lipases from germinating mustard (Brassica juncea) seeds were partially purified to 95% saturation using ammonium sulfate fractionation and were further purified using polyethylene glycol (PEG) fractionation. A 12.27-fold increase in the lipolytic activity of the purified lipase was observed for the 95S cut while 15.48-fold was observed for the PEG fraction. The values for the activities were 3008.78 U/mg and 3494.06 U/mg for 95S and PEG fractions respectively. The partially purified lipase was then cross-linked at p14 7.5, 70°C for 24 hours using 3:1 (v/v) 95S lipase solution to 25% glutaraldehydc solution ratio. The lipolytic activity of the optimized cross-linked lipase was found to have a value of 2115.30 U/mg enzyme using the standard lipase assay using olive oil as substrate. The cross-linked lipase exhibited a 9.37-fold increase in lipolytic activity relative to the soluble crude lipase. The optimum reaction condition for the cross-linked lipase was found to be at 60°C and 7.0 respectively. Lipolytic activity was determined using the standard lipase assay and was found to have an activity of 5879.14 U/mg cross-linked lipase. The cross-linked lipase was found to be catalytically active even after storage at room temperature for 4 months. Also, cross-linked lipase was found to remain catalytically active even after eight cycles of reuse with a three-fold decrease in lipolytic activity. Cross-linked lipase microcrystals cross-linked at the optimum cross-linking condition (p1-1 7.0. room temperature, 24 hours) was found to have an average crystal dimension of 154 X 109gm. Pores or tunnels in the crystals were found to have an average diameter of 34 gm. Pores were found to have the largest diameter relative to the other cross-linked samples. The large pores size may have caused the increase in lipolytic activity as there will be more site of contact between the enzyme and the substrate. Cross-linked lipase has a density of 0.7926 Went' and a crude protein content of 33.08%. Cross-linked enzyme was used in the transesterification of Jatropha seed oil and results were compared to that of the base catalyzed transesterification. A complete transesterification of the oil was observed after 3 hours and 4hours for the base catalyzed and cross-linked lipase transesterification respectively. The base catalyzed reaction proceeds faster however there was a difficulty in the separation of glycerol from the methyl esters. This problem was not encountered using cross-linked lipase catalyzed transesterification where glycerol and methyl esters were separated by centrifugation.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2009 C4 M36

Document Type

Thesis

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