Resumen de Effects of humic and oxalic acid in wood biodegradation by gloeophyllum trabeum
C Pozo, D Contreras, J Freer, F.J. Rodríguez
To degrade wood, brown rot fungi (BRF) have developed a mechanism based on low molar mass iron reducing compounds that promote Fenton reaction. These compounds, also solubilise Fe(III), in conjunction with oxalic acid, making it available for reaction. It have been postulated that the humic acids participates on wood biodegradation by BRF, acting in a similar way that the fungal compounds. In this work this effect and its interaction with oxalic acid were evaluated. The effect of humic acid and oxalic acid on the biodegradation of radiata pine chips by the BRF Gloeophyllum trabeum was evaluated using a two level factorial design. Absence or concentrations of 5 g/L and 0.05 M for humic acid and oxalic acid respectively, were evaluated; temperature (25°C) and initial pH (5.0) were kept constant. The responses were mass loss, holocellulose content and viscosity, measured after 30 days of biodegradation. The effects of the variables were determined using standardized coefficients of the polynomial equation, which were obtained through a multiple linear regression. All experiments were performed in quadruplicate and the obtained model was validated through an ANOVA test with a confidence interval of 95%. Oxalic acid was the factor that has a greater effect on these variables; it was able to extract metals from wood and to inhibit biodegradation when used without further treatment of humic acid. Humic acid impregnation increases the metal content in wood, but did not stimulate the wood biodegradation.
