Colocalizing incipient reactions in wood degraded by the brown rot fungus Postia placenta

Jonathan S. Schilling, Shona M. Duncan, Gerald N. Presley, Timothy R. Filley, Joel A. Jurgens, Robert A. Blanchette

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Brown rot fungi are theorized to use both free radicals and enzymes to degrade wood. If these incompatible agents are employed in sequence (enzymatic after oxidative) in order to avoid interaction, this should be resolvable spatially in rotting wood. To assess this, we used thin spruce wafers as substrates, with the largest face the transverse plane. Propped wafers were colonized from the bottom (tangential to grain) by Postia placenta, using wood cell orientation and gravity to slow fungal egress and accentuate spatial gradients. After brief colonization, wafers were cut into 1-mm strips progressing up the wafer, and subsectioned for complementary analyses. Analyses included fungal growth, pH, cellulase activity, and wood modifications attributable to non-enzymatic mechanisms. Hyphae were imaged using confocal microscopy of fluorophore-tagged chitin. Dilute alkali solubility and lignin demethylation were measured as proxies (consequences) of carbohydrate depolymerization and lignin oxidation, respectively. Because P.placenta lacks genes for cellobiohydrolases, endoglucanase (EG) activity was measured. In composites of reassembled sections, hyphal fronts and apparent depolymerization preceded EG and lignin demethylation fronts by more than 6mm. Although detection limits are a caveat when implicating novel fungal metabolites, results encourage and provide methodology for targeting this interesting leading edge of cellulolysis.

Original languageEnglish (US)
Pages (from-to)56-62
Number of pages7
JournalInternational Biodeterioration and Biodegradation
Volume83
DOIs
StatePublished - Sep 2013

Bibliographical note

Funding Information:
This work was made possible by US Department of Energy (DOE) grants GO18088 from the Biomass Research and Development Initiative (BRDI) and DE SC0004012 Early Career from the Biological and Ecological Research (BER) program , along with an Early Career grant ( RC 008-11 ) from the Initiative for Renewable Energy and the Environment (IREE), a program of the Institute on the Environment (IonE) at the University of Minnesota. The authors would like to thank Dr. Charles Abbas from Archer Daniels Midland (ADM) Company and Mr. Justin Kaffenberger for technical input, along with Mr. Benjamin Held for his help in confocal image retrieval and interpretation.

Keywords

  • Brown rot
  • Decay
  • Fenton
  • GH61
  • Glycosyl hydrolase
  • Polysaccharide monooxygenase

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