Abstract

The biological decomposition of lignocellulosic materials caused by basidiomycetes plays an essential role in the carbon cycle. Brown rot fungi represent important agents in the biodegradation of wood products and standing coniferous trees in natural ecosystems. The initial moisture content of the wood is an important factor in the degradation process. In this work, the effects of initial moisture content of Eucalyptus grandis sapwood on decay by two brown rot fungi Gloeophyllum trabeum and Laetiporus sulphureus were studied over a 10-month period. The fungal activity was evaluated, through wood weight loss, moisture content, anatomical changes (scan electronic and fluorescence microscopy) and Fourier-transform infrared spectroscopy. Weight loss increased through the 10-month test for both fungi, Laetiporus sulphureus producing higher mass losses. Colonization of the wood by both fungi started below the fiber saturation range. It was observed that the initial moisture content of the wood influenced the rate of deterioration: the wet samples showed higher weight loss compared to the dry samples. Changes in the chemical composition and structure of cell walls were detected. The initial moisture content of the substrate affected the development of the fungi, slowing their growth.

Highlights

  • Universidad del Bío-BíoWood is widely used for construction; its biological origin makes it vulnerable to attack by decomposing fungi, those that cause brown and white rot

  • Water availability becomes critical for fungi, if water is exclusively limited to the cell wall and no free water is present in the cell lumens, which is called fiber saturation point (FSP) (Stienen et al 2014)

  • The changes caused by L. sulphureus and G. trabeum in the dry and wet wood of E. grandis were found through the traditional gravimetric method, FTIR spectrometry and the different types of microscopy

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Summary

Introduction

Universidad del Bío-BíoWood is widely used for construction; its biological origin makes it vulnerable to attack by decomposing fungi, those that cause brown and white rot. The risk of deterioration by fungi can be quantified through environmental parameters such as moisture content and temperature of the wood (Brischke et al 2017). Numerous studies have examined the minimum moisture contents that allow fungal colonization and wood deterioration (Walchli 1980, Huckfeldt et al 2005, Huckfeldt and Schmidt 2015, Höpken et al 2016, Brischke et al 2017, Thybring 2017). The effect of the initial moisture content of the wood on the decay rate is generally studied in the early stages of the process, analyzed through weight loss or mechanical properties

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