Biocatalysts are important tools for harnessing the potential of wood fibres since they can perform specific reactions with low environmental impact. Challenges to bioconversion technologies as applied to wood fibres include low accessibility of plant cell wall polymers and the heterogeneity of plant cell walls, which makes it difficult to predict conversion efficiencies.
White-rot fungi are among the most efficient degraders of plant fibre (lignocellulose), capable of degrading cellulose, hemicellulose and lignin. Phanerochaete carnosa is a white-rot fungus that, in contrast to many white-rot fungi that have been studied to date, was isolated almost exclusively from fallen coniferous trees (softwood). While several studies describe the lignocellulolytic activity of the hardwood-degrading, model white-rot fungus Phanerochaete chrysosporium, the lignocellulolytic activity of P. carnosa has not been investigated.
An underlying hypothesis of this thesis is that P. carnosa encodes enzymes that are particularly well suited for processing softwood fibre, which is an especially recalcitrant feedstock, though a major resource for Canada. Moreover, given the phylogenetic similarity of P. carnosa and P. chrysosporium, it is anticipated that the identification of pertinent enzymes for softwood degradation can be more easily conducted. In particular, this project describes the characterization of P. carnosa in terms of the growth conditions that support lignocellulolytic activity, the effect of enzymes secreted by P. carnosa on the chemistry of softwood feedstocks, and the characterization of the corresponding secretome using proteomic techniques. Through this study, cultivation methods for P. carnosa were established and biochemical assays for protein activity and quantification were developed. Analytical methods, including FTIR and ToF-SIMS were used to characterize wood samples at advancing stages of decay, and revealed preferential degradation of lignin in the early stages of growth on all softwoods analyzed. Finally, an in depth proteomic analysis of the proteins secreted by P. carnosa on spruce and cellulose established that similar sets of enzyme activities are elicited by P. carnosa grown on different lignocellulosic substrates, albeit to different expression levels.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31852 |
| Date | 10 January 2012 |
| Creators | Mahajan, Sonam |
| Contributors | Master, Emma |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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