Ahmad, Mark (2010) Development of novel assays for lignin breakdown and identification of a new bacterial lignin degrading enzyme. PhD thesis, University of Warwick.

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Abstract

Two novel spectrophotometric assays have been developed for high throughput
screening of microbial lignin degradation. The first assay involves fluorescently
labelled lignin, which gives a time dependent increase in fluorescence with
lignin degradation. The second involves nitrated lignin where an increase is seen
at 430nm when lignin is broken down. These assays have allowed identification
of a number of new strains of lignin degrading bacteria including R. jostii
RHA1. They have also allowed the comparison of bacterial and fungal
degraders and a study of lignin specificity.
Bioinformatics has been used to identify two putative lignin degrading enzymes
in R. jostii RHA1. Their role in lignin degradation was investigated by assaying
of gene knockouts. This led to the detailed study of a new recombinant
peroxidase, DypB, using lignin, lignocellulose and lignin dimer model
substrates. This represents the first recombinant bacterial lignin degrading
enzyme to be characterised.
In addition methods for studying the products of lignin breakdown by HPLC,
GC/MS and LC/MS have been developed. This has led to the identification of
several low molecular weight aromatic products including ferulic acid. It has
also been shown that the products released from lignin model compounds can be
controlled by addition of the reductive enzyme diaphorase.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Lignin -- Biodegradation, Peroxidase
Official Date:	September 2010
Dates:	Date Event September 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bugg, Tim
Extent:	237 leaves : ill., charts
Language:	eng

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