Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants

The oxidoreductases are widely recognized for their capability to degrade organic pollutants. However, in order to enhance their biochemical stability and reusability to degrade organic pollutants especially in non-conventional solvents, the immobilization is absolutely necessary. The immobilization...

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Main Author:	Mohidem, Nur Atikah
Format:	Thesis
Published:	2010
Subjects:	Unspecified
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spelling	my-utm-ep.264362017-08-16T03:45:31Z Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants 2010 Mohidem, Nur Atikah Unspecified The oxidoreductases are widely recognized for their capability to degrade organic pollutants. However, in order to enhance their biochemical stability and reusability to degrade organic pollutants especially in non-conventional solvents, the immobilization is absolutely necessary. The immobilization through encapsulation in sol-gel silica matrices was adopted based on several reports which indicated that enzymes such as lipase encapsulated in sol-gel silica matrices resulted enhanced their catalytic activity and stability. The oxidoreductases namely laccase was used exclusively in this study, while peroxidase and tyrosinase were used as comparisons. The catalytic activity of laccase and peroxidase was assayed using 2,6- dimethoxyphenol as a substrate, while the catalytic activity of the tyrosinase was assayed using L-tyrosine as a substrate. The resulted sol-gel laccase gave larger pore size (96.79 A) and strong intensity of the Fourier Transform Infrared (FTIR) spectra. The catalytic activity and stability of the sol-gel laccase and sol-gel peroxidase were proven to be significantly enhanced to 100* and 20 respectively; however the sol-gel tyrosinase was showed no measurable catalytic activity. No significant leaching of the encapsulated laccase was observed over time, suggesting that the laccase molecule were sterically confined in small pores. It was also found that the catalytic activity and stability of the sol-gel laccase could be enhanced in the presence of additives and the use of different precursors did not show any significant difference on the laccase catalytic activity. The sol-gel laccase yielded lower Km (0.72) and increased in Vmax (1779.36) compared to the free laccase. The present study also showed that the sol-gel laccase was catalytically active in non-conventional solvents (e.g. organic solvents and ionic liquids). The degradation of o-chorophenol as a model organic pollutant was also conducted in aqueous and non-conventional solvents. The High Performance Liquid Chromatography (HPLC) was used to determine the concentration of o-chlorophenol. The degree of degradation was measured by the decrease in the concentration of o-chlorophenol against its initial concentration. The results showed that the sol-gel laccase gave higher degradation than free laccase either in aqueous or non-conventional solvents. It was found that the degradation of o-chlorophenol in organic solvents either by the free or the sol-gel laccase required water and the reaction temperature significantly affected the biodegradation capability of the free and sol-gel laccase. It was also found that the sol-gel laccase could be used 10 times and fairly stable. 2010 Thesis http://eprints.utm.my/id/eprint/26436/ http://libraryopac.utm.my/client/en_AU/main/search/results?qu=Catalytic+activity+and+stability+of+encapsulated+oxidoreductases+for+biodegradation+of+organic+pollutants&te= masters Universiti Teknologi Malaysia, Faculty of Chemical Engineering Faculty of Chemical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
topic	Unspecified
spellingShingle	Unspecified Mohidem, Nur Atikah Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
description	The oxidoreductases are widely recognized for their capability to degrade organic pollutants. However, in order to enhance their biochemical stability and reusability to degrade organic pollutants especially in non-conventional solvents, the immobilization is absolutely necessary. The immobilization through encapsulation in sol-gel silica matrices was adopted based on several reports which indicated that enzymes such as lipase encapsulated in sol-gel silica matrices resulted enhanced their catalytic activity and stability. The oxidoreductases namely laccase was used exclusively in this study, while peroxidase and tyrosinase were used as comparisons. The catalytic activity of laccase and peroxidase was assayed using 2,6- dimethoxyphenol as a substrate, while the catalytic activity of the tyrosinase was assayed using L-tyrosine as a substrate. The resulted sol-gel laccase gave larger pore size (96.79 A) and strong intensity of the Fourier Transform Infrared (FTIR) spectra. The catalytic activity and stability of the sol-gel laccase and sol-gel peroxidase were proven to be significantly enhanced to 100* and 20 respectively; however the sol-gel tyrosinase was showed no measurable catalytic activity. No significant leaching of the encapsulated laccase was observed over time, suggesting that the laccase molecule were sterically confined in small pores. It was also found that the catalytic activity and stability of the sol-gel laccase could be enhanced in the presence of additives and the use of different precursors did not show any significant difference on the laccase catalytic activity. The sol-gel laccase yielded lower Km (0.72) and increased in Vmax (1779.36) compared to the free laccase. The present study also showed that the sol-gel laccase was catalytically active in non-conventional solvents (e.g. organic solvents and ionic liquids). The degradation of o-chorophenol as a model organic pollutant was also conducted in aqueous and non-conventional solvents. The High Performance Liquid Chromatography (HPLC) was used to determine the concentration of o-chlorophenol. The degree of degradation was measured by the decrease in the concentration of o-chlorophenol against its initial concentration. The results showed that the sol-gel laccase gave higher degradation than free laccase either in aqueous or non-conventional solvents. It was found that the degradation of o-chlorophenol in organic solvents either by the free or the sol-gel laccase required water and the reaction temperature significantly affected the biodegradation capability of the free and sol-gel laccase. It was also found that the sol-gel laccase could be used 10 times and fairly stable.
format	Thesis
qualification_level	Master's degree
author	Mohidem, Nur Atikah
author_facet	Mohidem, Nur Atikah
author_sort	Mohidem, Nur Atikah
title	Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
title_short	Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
title_full	Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
title_fullStr	Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
title_full_unstemmed	Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
title_sort	catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants
granting_institution	Universiti Teknologi Malaysia, Faculty of Chemical Engineering
granting_department	Faculty of Chemical Engineering
publishDate	2010
_version_	1747815475962707968

Catalytic activity and stability of encapsulated oxidoreductases for biodegradation of organic pollutants

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