Protection of Wood from Microorganisms by Laccase-Catalyzed Iodination

Abstract

bIn the present work, Norway spruce wood (Picea abies L.) was reacted with a commercial Trametes versicolor laccase in the presence of potassium iodide salt or the phenolic compounds thymol and isoeugenol to impart an antimicrobial property to the wood surface. In order to assess the efficacy of the wood treatment, a leaching of the iodinated and polymerized wood and two biotests including bacteria, a yeast, blue stain fungi, and wood decay fungi were performed. After laccasecatalyzed oxidation of the phenols, the antimicrobial effect was significantly reduced. In contrast, the enzymatic oxidation of iodide (I ؊ ) to iodine (I 2 ) in the presence of wood led to an enhanced resistance of the wood surface against all microorganisms, even after exposure to leaching. The efficiency of the enzymatic wood iodination was comparable to that of a chemical wood preservative, VP 7/260a. The modification of the lignocellulose by the laccase-catalyzed iodination was assessed by the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The intensities of the selected lignin-associated bands and carbohydrate reference bands were analyzed, and the results indicated a structural change in the lignin matrix. The results suggest that the laccase-catalyzed iodination of the wood surface presents an efficient and ecofriendly method for wood protection.

Enzymatic biocatalysis of bamboo chemical constituents to impart antimold properties

“…The formation of aromatic organo-iodine complexes which can impart antifungal properties to wood has been previously reported (Ihssen et al 2014;Schubert et al 2012). In addition, the XPS analyses in the Section XPS analysis results of the samples demonstrated possible formation of C-I covalent bonds.…”

“…In an innovative and seminal research, Schubert et al (2012) and Ihssen et al (2014) demonstrated that KI could be bound to wood using the laccase-mediator system. In this way, KI would then provide antimicrobial surfaces even after leaching.…”

“…In this way, KI would then provide antimicrobial surfaces even after leaching. The research of Schubert et al (2012) and Ihssen et al (2014) was some of the first to be conducted which demonstrated a new and bio-based technology to fix iodine residues onto Norway spruce wood for potential protection in a safe and environmentally acceptable manner. Their work was focused on wood rather than bamboo or grasses but demonstrated the effectiveness of such treatments against a wide variety of fungi including blue-stain, wood decay, yeasts, and gram-positive and gram-negative bacteria.…”

Prediction and optimization of the laccase-mediated synthesis of the antimicrobial compound iodine (I2)

“…Based on previous studies (Ihssen et al, 2014;Schubert et al, 2012a), the variables and their levels selected for the study of laccase-mediated iodine (I 2 ) synthesis were: enzyme concentration (50-100 U L −1 Trametes sp. laccase, ASA Spezialenzyme GmbH, Germany, determined with the ABTS assay), mediator concentration (acetosyringone ACS, 30-70 M), educt concentration (potassium iodide, 20-50 mM) and pH (3-7).…”

“…vanillin) or native wood (e.g. Norway spruce) resulted in iodinated compounds with antifungal activity and leaching resistant antimicrobial wood surfaces, respectively (Ihssen et al, 2014;Schubert et al, 2012a). The synthesis of iodine depends on different parameters, thus analysis of important process parameters for optimization is essential.…”