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Ecology and Epidemiology

Associations Among Bacteria, Yeasts, and Basidiomycetes During Wood Decay. Robert A. Blanchette, Research Assistant, Department of Plant Pathology, Washington State University, Pullman, WA 99164; C. Gardner Shaw, professor, Department of Plant Pathology, Washington State University, Pullman, WA 99164. Phytopathology 68:631-637. Accepted for publication 27 September 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-631.

Bacteria, yeasts, and basidiomycetes were closely associated during the decay of dead coniferous wood. In the laboratory, significant increases in decay (weight loss) and a marked stimulatory effect on mycelial growth was observed after 5 mo in wood decay treatments combining bacteria (Enterobacter spp.) and yeasts (Saccharomyces bailii var. bailii and Pichia pinus) with the basidiomycetes, Coriolus versicolor, Hirschioporus abietinus, or Poria placenta. Substrates used were wood chips from slash less than 1 yr, between 1 and 2 yr, and over 25 yr old. The amount of mycelia present was determined quantitatively by assaying for glucosamine. Up to 200% more fungal growth was obtained in treatments combining bacteria, yeasts, and a basidiomycete than with single basidiomycetes. Substantially more decay (2-10 fold) occurred with the brown-rot fungus, P. placenta, than with the white-rot fungi, C. versicolor or H. abietinus. The age of the chips and the species of wood used affected the rate of decomposition. Decay was more rapid in wood chips from slash less than 2 yr old than in that over 25 yr old. Bacteria and yeasts were responsible for increases of decay by the respective basidiomycete in wood chips of all age classes. Scanning electron microscopy revealed mutualistic associations among microorganisms. Bacteria and yeasts were located only in tracheid cell walls decayed by basidiomycetous hyphae. Similar associations of bacteria, yeasts, and mycelia were observed in logs naturally infected by four basidiomycetes, C. versicolor, H. abietinus, Cryptoporus volvatus, and Fomitopsis pinicola.

Additional keywords: scanning electron microscopy, brown-rot fungi, white-rot fungi, synergism, deterioration, forest residue management, glucosamine analysis, conifers.