The influence of moisture content and wood pH variation on fungal melanin formation in wood substrates

IRG/WP 11-10759

D Tudor, S C Robinson, P A Cooper

Wood decay patterns are strongly influenced by the conditions of the wood substrate, including moisture content and pH. In an antagonistic environment some fungi respond with pigment formation that helps to isolate and protect their mycelium. This is often associated with slower fungal growth and delay of wood mass loss. Dark colored melanin is the most common pigment formed by wood decay fungi, and it is produced in consecutive granule depositions in the lumens of the wood cells to form distinctive zone lines. To investigate the melanin formation, sugar maple and beech samples were inoculated with different strains of Trametes versicolor and Xylaria polymorpha. To test the influence of pH on melanin formation, wood samples were adjusted with buffer solutions to different pH values; to test the influence of moisture content in pigment formation, wood samples were incubated at different vermiculite substrate moisture contents. Maximum pigment production occurred at pH 4.5 for beech and pH 5 for sugar maple inoculated with Trametes versicolor, while Xylaria polymorpha produced external pigmentation in beech treated with buffer at pH 5. Wood samples with the lowest moisture content had higher black pigment accumulation.


Keywords: fungal melanin, wood pH, wood moisture content, Trametes versicolor, Xylaria polymorpha, pigment, spalting

Conference: 11-05-08/12 Queenstown, New Zealand


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