Abstract
ABSTRACT Ergosterol is responsible for important functions in the fungal plasma membrane. The influence of fungitoxic agents on membrane ergosterol content is one of the most important mechanisms of antifungal action and its knowledge allows the generation of products that associate active compounds of different mechanisms, consequently improving the effectiveness of wood preservatives. Therefore, this study optimized a method for quantifying ergosterol in wood-decay fungi. The white-rot species selected were Ganoderma applanatum and Trametes versicolor, while the brown-rot were Gloeophyllum trabeum and Lentinus lepideus. Mycelial discs of each species were transferred to Petri dishes containing a cellophane-covered potato-dextrose-agar medium. Mycelia of each fungus were collected, weighed, and transferred to test tubes with 5 mL of 25% alcoholic potassium hydroxide. The tubes were vortexed for 5 min, subjected to ultrasound for 5 min, incubated at 85 °C for 4 h, followed by the addition of 2 mL of sterile distilled water and 5 mL of n-heptane and subsequent ultrasound shaking for 2 min. The n-heptane layer was analyzed by UV spectrophotometry between 230 and 300 ηm. The blank sample only contained n-heptane. The mycelia wet weight of the fungi ranged from 0.061 to 0.296 g. Ergosterol content was 0.007% for Lentinus lepideus and 0.004% for the other species. The absorbance was higher than the ones observed in the blank for all samples. The adapted method was efficient for ergosterol extraction.
Highlights
Different biological agents can attack wood-based products, including wood-decay fungi (Stangerlin et al, 2013)
No significant differences were found in mycelial growth in PDA among G. applanatum, T. versicolor, G. trabeum, and L. lepideus with and without the cellophane membrane (Table 1)
The procedure tested in this study obtained mycelial wet weights of 0.079 ± 0.225, 0.296 ± 0.0267, 0.079 ± 0.0225, and 0.061 ± 0.0044 g for G. applanatum, T. versicolor, G. trabeum, and L. lepideus, respectively (Figure 1)
Summary
Different biological agents can attack wood-based products, including wood-decay fungi (Stangerlin et al, 2013). These organisms can cause serious damage to wooden structures, which may result in considerable economic and resource losses (Cheng et al, 2008). These fungi belong to the class Basidiomycetes and are classified as white and brown rots (Oliveira et al, 2005). The white-rot group is characterized by the capacity to degrade lignin, hemicellulose, and cellulose, while the brown-rot fungi are characterized by the degradation of wood polysaccharides (Martínez et al, 2005). Some preservatives have high toxicity, research is necessary to obtain alternative fungitoxic agents that are effective in combating wood rot (Brand et al, 2006; Xie et al, 2017)
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