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Phone: (608) 231-9200
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Institute for Microbial and Biochemical Techology

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 17 publications associated with this project.

Principal Investigator:
Kenneth E. Hammel

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

Publication YearTitleDate Posted
20142D-NMR Demonstration of Lignin Removal from Wood and Non-wood plant Feedstocks by Fungal Versatile Peroxidase10/01/14
2014A Highly Diastereoselective Oxidant Contributes to Ligninolysis by the White Rot Basidiomycete Ceriporiopsis subvermispora10/01/14
2016Acridine Orange Indicates Early Oxidation of Wood Cell Walls by Fungi09/07/16
2017An optical method for carbon dioxide isotopes and mole fractions in small gas samples: tracing microbial respiration from soil, litter, and lignin.10/05/17
2015Basidiomycete DyPs: Genomic diversity, structural-functional aspects, reaction mechanism and environmental significance12/07/15
2016Construction of a genetic linkage map and analysis of quantitative trait loci associated with the agronomically important traits of Pleurotus eryngii07/12/16
2013Evidence from Serpula lacrymans that 2,5-Dimethoxyhydroquinone Is a Lignocellulolytic Agent of Divergent Brown Rot Basidiomycetes09/05/13
2017Exploring the hypothesis that limiting diffusion of fungal oxidants underlies decay resistance in acetylated wood10/06/17
2013Formation of a tyrosine adduct involved in lignin degradation by Trametopsis cervina lignin peroxidase: a novel peroxidase activation mechanism09/09/13
2018Fungal lignin peroxidase does not produce the veratryl alcohol cation radical as a diffusible ligninolytic oxidant07/26/18
2016Iron addition to soil specifically stabilized lignin05/24/16
2015Lignin decomposition is sustained under fluctuating redox conditions in humid tropical forest soils09/25/15
2014Ligninolytic peroxidase genes in the oyster mushroom genome: heterologous expression, molecular structure, catalytic and stability properties, and lignin-degrading ability09/16/14
2016Localizing gene regulation reveals a staggered wood decay mechanism for the brown rot fungus Postia placenta07/05/17
2015Regulation of Gene Expression during the Onset of Ligninolytic Oxidation by Phanerochaete chrysosporium on Spruce Wood12/15/15
2013Spatial mapping of extracellular oxidant production by a white rot basidiomycete on wood reveals details of ligninolytic mechanism05/14/13
2014What Basidiomycete Genomes Teach us about Wood Biodegradation Mechanisms10/01/14

Project Summaries last modified: 08-22-2018