Resistance of rubberwood (Hevea brasiliensis) treated with chitosan or silane against surface molds

Abstract

The aim of this study was to determine the efficacy of chitosan and methoxysilane in the prevention of surface mold growth on rubberwood. Three different chitosan samples were tested; C1 (Mw 37 kDa), C2 (Mw 5.4 kDa) and C3 (Mw 3.5 kDa). Radial growth inhibition assay of the chitosan samples was investigated at concentrations ranging from 0.063 to 0.5 %w/v against Aspergillus niger BAM 4 and Penicillium decumbens CBS 121928. Chitosan samples C1 and C3 exhibited strong antifungal activity against both molds. Rubberwood samples were either vacuum or dip treated with varying concentrations of chitosan or silane solution. The content of chitosan in wood showed that after the leaching test, chitosan was well retained in both vacuum and dip treated wood. The concentration of silicon in wood showed similar results. The vacuum treated wood samples with chitosan C1 and C3 at 1 %w/v concentration had strong resistance against A. niger BAM 4. However, dip treated rubberwood samples with 2 %w/v chitosan solutions showed lower resistance against A. niger BAM 4. On the other hand, both vacuum and dip treated rubberwood samples with chitosan had no resistance against P. decumbens CBS 121928. The silane treated wood samples showed no resistance to fungal growth.

Propolis and Organosilanes as Innovative Hybrid Modifiers in Wood-Based Polymer Composites

“…According to literature data, wood impregnated with alkoxysilanes shows no resistance to moulds, such as Alternaria alternata , Cladosporium herbarum , A. niger , Penicillium decumbenes and Penicillium brevicompactum [ 50 , 52 , 53 , 54 ]. In turn, Ghosh et al [ 55 ] reported that impregnation with an amino-silicone macro-emulsion resulted in a certain resistance to growth of moulds (including A. versicolor , Ulocladium strum and Aureobasidium pullulans ) on wood surfaces, whereas wood treated with the same concentrations of silicone quat micro-emulsion and alkyl-modified silicone macro-emulsion exhibited comparatively lower resistance.…”

“…The concentration of silicon (coming from organosilane compounds) in wood impregnated with silanes and the propolis-silane formulations determined by flame atomic absorption spectrometry is presented in Table 2. Analysis of Si concentration in wood samples treated with silicon compounds is a useful tool in assessment their presence in wood structure [36,49,50]. The silicon concentrations in treated wood indicated that wood samples impregnated with both silane-propolis formulations contained higher amounts of Si compared to wood treated with silicon compounds without the propolis extract.…”

Antifungal Agents in Wood Protection—A Review

“…Chitosan is the most frequently studied polymer of animal origin as a component of wood preservatives. The literature data report that the antifungal activity of chitosan as a wood preservative depends on its concentration, molecular weight, the solvent used for the chitosan dissolved, or fungal strain [ 21 , 90 , 153 , 154 , 155 , 156 ]. The increase in chitosan concentration and molecular weight increases its fungicidal activity [ 21 , 154 ].…”

“…Among the three different chitosan samples, two chitosan dissolved in weak acid solutions showed strong antifungal activity against A. niger and Penicillium decumbens , while chitosan in the form of an aqueous oligomer solution exhibited a 100% reduction in the colony size only against P. decumbens in the radial growth inhibitor assay. On the other hand, rubberwood ( Hevea brasiliensis ) treated with an acid chitosan solution showed resistance against A. niger , and no resistance against P. decumbens [ 153 ]. Wood samples impregnated with 5% chitosan solution showed resistance against the brown rot fungi C. puteana , T. versicolor , and P. placenta , while wood treated with a lower concentration of chitosan exhibited no resistance to the tested fungi [ 21 , 157 ].…”

Chitosan–caffeine formulation as an ecological preservative in wood protection

“…The literature data showed that chitosan limited the growth of decay fungi (C. puteana, P. placenta and T. versicolor); however, the mass loss of treated wood was related to chitosan concentration, strain of fungi and molecular weight of chitosan (Alfredsen et al 2004;Eikenes et al 2005). The molecular size of chitosan and its concentration also impact the anti-mold properties of chitosan-treated wood (Gorgij et al 2014;El-Gamal et al 2016;Oldertrøen et al 2017). Chitosan was also applied to wood treatment in combination with other substances, including cinnamaldehyde, polyethylene glycol, propolis extract and silver nanoparticles (Silva-Castro et al 2018;Casado-Sanz et al 2019;Bi et al 2021;Fang et al 2021).…”