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Institute for Microbial and Biochemical Techology
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Project Title :
Oxidative systems of wood decay fungi Project Number : FPL-4712-2B Status : NEW Start Date : 10-01-2012 End Date : 09-30-2019 View the 19 publications associated with this project. |
Principal Investigator: Kenneth E. Hammel |
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| Non Technical Summary | ||
| This research seeks to identify and understand the oxidative systems of wood decay fungi so that we can increase the efficacy of these naturally-occurring organisms in bioconversion technologies, devise new environmentally-sound ways to protect wood in use, and understand natural processes that speed or retard the decomposition of forest litter. | ||
| Objectives Summary | ||
| The objectives of this research are to understand how lignocellulose-degrading fungi contribute to global carbon cycling, and also to determine which aspects of fungal metabolism might be optimized to obtain high-performance organisms and enzymes for technological applications. The principal research needs in this area are to identify, at the genetic and biochemical levels, (1) the systems that selective white-rot fungi use to modify wood and (2) the systems brown rot fungi use to penetrate the lignin in wood and depolymerize the cellulose. | ||
| Approach Summary | ||
| We will address these problems in the following ways:This research involves basic investigations into the mechanisms of lignin and cellulose degradation by selected white rot and brown rot fungi. Emphasis will be on (a) elucidating the chemistry of extracellular oxidative systems that these fungi produce, and (b) identifying the genes and enzymes that are responsible for producing the oxidants. The underlying hypothesis for the work is that, because enzymes such as cellulases are too large to penetrate sound wood, decay fungi produce low-molecular-weight metabolites that can penetrate the lignin matrix in wood and generate oxidants in situ to initiate depolymerization of lignin or cellulose. Enzymes presumably come into play later in the decay process, when the wood has become more permeable. Recent work from this unit has shown that the oxidant-generating metabolites in several wood decay fungi are hydroquinones, which reduce both ferric iron and oxygen in the wood. Subsequent reactions between ferrous iron and reduced oxygen species then produce hydroxyl radicals, which are strong oxidants that cleave both cellulose and lignin. Research also suggests that some fungi employ less reactive small oxidants to attack wood polymers. However, it is not yet known how widespread these biodegradative mechanism are among wood decay fungi, or whether different groups of fungi employ fundamentally different small oxidants. 1. Begin to elucidate the biochemical pathways fungi use to biosynthesize hydroquinones. These pathways could be key targets for inhibitors of wood decay, which might then find use as new wood preservatives. 2. Determine, by screening a variety of white, brown, and soft rot fungi, how widespread the hydroquinone-dependent biodegradative mechanism is. Identify new biodegradative mediators that these fungi may use instead of hydroquinones.3. Determine, using recently developed multidimensional nuclear magnetic resonance spectroscopic techniques, whether chemical changes in lignin after fungal attack indicate the operation of particular oxidants.4. Develop fluorogenic probes that are selectively attacked by different oxidants, and use these probes on wood, in conjunction with fluorescence microscopic analysis, to gain insight into which oxidants various fungi produce.5. Identify and characterize new metabolic pathways involved in wood decay that might serve as targets for inhibition of decay or provide new opportunities for bioconversion technologies. Specific emphasis will be on extracellular carbohydrate metabolism related to production of peroxide, reductants, and organic acids important during incipient decay of lignocellulosics.6. Communicate the findings in high-quality scientific papers in refereed journals and in lectures before a variety of audiences. |
Publications associated with this Project
| Project Summaries last modified: 08-22-2018 |