Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification

Lignin is a complex phenylpropanoid heteropolymer entangled around cellulose and hemicellulose fibre. It is recalcitrant towards degradation, thus pose a major problem in obtaining good quality fibre. Moreover, the conventional degradation methods (chemically and mechanically) consume vast amount of...

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Main Author: Ishak, Nadiah
Format: Thesis
Language:English
English
English
Published: 2018
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spelling my-uthm-ep.2352021-07-13T03:16:01Z Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification 2018-07 Ishak, Nadiah QP501-801 Animal biochemistry Lignin is a complex phenylpropanoid heteropolymer entangled around cellulose and hemicellulose fibre. It is recalcitrant towards degradation, thus pose a major problem in obtaining good quality fibre. Moreover, the conventional degradation methods (chemically and mechanically) consume vast amount of chemicals and energy which have deleterious effects to the environment. The aim of this research is to identify an alternative process for lignin removal by employing ligninase produced by lignin-depolymerising bacteria isolated within the gut of wood feeding insect, Rynchophorus ferrugineus. In this study, four bacterial species capable of depolymerising lignin were isolated, identified and characterised as Klebsiella pneumoniae, Pseudomonas citronellolis, Enterobacter oryzae, and Serratia mercescens. The production of ligninase enzymes (lignin peroxidase, manganese peroxidase and laccase) in all species were optimised using response surface methodology (RSM). The results revealed maximal production of ligninase is achieved at optimal pH of 5 to 6 and optimal temperature of 40 °C after 7 days of incubation. The ability of each specie to remove lignin in agrowastes (cogon grass (CG) and oil palm leaves (OPL)) was validated through UV-Vis spectrophotometer, FTIR and SEM analyses. The results showed that the gut microbes were solely able to degrade lignin with 30 to 60% in OPL and CG respectively, in which the highest delignification is obtained by the combination of all species. Furthermore, traces of small molecular weight compounds generated after the enzymatic breakdowns were identified through HPLC and GC-MS analysis as part of the complementary study. Through the identification of metabolites produced, the conversion pathways of lignin polymer to various aromatic and non-aromatic compounds during the breakdown were also proposed. The findings of this research can be made applicable to the pulp and paper industries thus encouraging the use of green and sustainable technology. The identification of breakdown metabolites could be exploited in the valorization of lignin promoting the concept of „waste to wealth‟. 2018-07 Thesis http://eprints.uthm.edu.my/235/ http://eprints.uthm.edu.my/235/1/24p%20NADIAH%20ISHAK.pdf text en public http://eprints.uthm.edu.my/235/2/NADIAH%20ISHAK%20COPYRIGHT%20DECLARATION.pdf text en staffonly http://eprints.uthm.edu.my/235/3/NADIAH%20ISHAK%20WATERMARK.pdf text en validuser phd doctoral Universiti Tun Hussein Onn Malaysia Fakulti Teknologi Kejuruteraan
institution Universiti Tun Hussein Onn Malaysia
collection UTHM Institutional Repository
language English
English
English
topic QP501-801 Animal biochemistry
spellingShingle QP501-801 Animal biochemistry
Ishak, Nadiah
Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
description Lignin is a complex phenylpropanoid heteropolymer entangled around cellulose and hemicellulose fibre. It is recalcitrant towards degradation, thus pose a major problem in obtaining good quality fibre. Moreover, the conventional degradation methods (chemically and mechanically) consume vast amount of chemicals and energy which have deleterious effects to the environment. The aim of this research is to identify an alternative process for lignin removal by employing ligninase produced by lignin-depolymerising bacteria isolated within the gut of wood feeding insect, Rynchophorus ferrugineus. In this study, four bacterial species capable of depolymerising lignin were isolated, identified and characterised as Klebsiella pneumoniae, Pseudomonas citronellolis, Enterobacter oryzae, and Serratia mercescens. The production of ligninase enzymes (lignin peroxidase, manganese peroxidase and laccase) in all species were optimised using response surface methodology (RSM). The results revealed maximal production of ligninase is achieved at optimal pH of 5 to 6 and optimal temperature of 40 °C after 7 days of incubation. The ability of each specie to remove lignin in agrowastes (cogon grass (CG) and oil palm leaves (OPL)) was validated through UV-Vis spectrophotometer, FTIR and SEM analyses. The results showed that the gut microbes were solely able to degrade lignin with 30 to 60% in OPL and CG respectively, in which the highest delignification is obtained by the combination of all species. Furthermore, traces of small molecular weight compounds generated after the enzymatic breakdowns were identified through HPLC and GC-MS analysis as part of the complementary study. Through the identification of metabolites produced, the conversion pathways of lignin polymer to various aromatic and non-aromatic compounds during the breakdown were also proposed. The findings of this research can be made applicable to the pulp and paper industries thus encouraging the use of green and sustainable technology. The identification of breakdown metabolites could be exploited in the valorization of lignin promoting the concept of „waste to wealth‟.
format Thesis
qualification_name Doctor of Philosophy (PhD.)
qualification_level Doctorate
author Ishak, Nadiah
author_facet Ishak, Nadiah
author_sort Ishak, Nadiah
title Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
title_short Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
title_full Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
title_fullStr Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
title_full_unstemmed Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
title_sort application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
granting_institution Universiti Tun Hussein Onn Malaysia
granting_department Fakulti Teknologi Kejuruteraan
publishDate 2018
url http://eprints.uthm.edu.my/235/1/24p%20NADIAH%20ISHAK.pdf
http://eprints.uthm.edu.my/235/2/NADIAH%20ISHAK%20COPYRIGHT%20DECLARATION.pdf
http://eprints.uthm.edu.my/235/3/NADIAH%20ISHAK%20WATERMARK.pdf
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