Migration of methylene bis thiocyanate in wood and its effect on a wood degrading fungus

Abstract

The mobility and concentrations of methylene bis thiocyanate (MBT) at diVerent depths of wood billets (200 mm long, 40 mm in diameter) of Pinus radiata were determined using NMR spectroscopy and ICP-ASE. Results were then correlated with the eVect of wood MBT concentrations on growth of O. Xoccosum in a bioassay using stereomicroscopy and confocal laser scanning microscopy (CLSM). The 13 C NMR spectra showed the presence or the absence of MBT in wood but it was unable to detect small concentrations. ICP-ASE, however produced quantitative data across the depth (40 mm) of the wood billets tested. Within 7 days of storage, MBT penetrated from surface to pith but showed signiWcantly higher concentrations of MBT in surface wood compared to pith wood. Present study highlighted the beneWt of using CLSM for fungal detection in wood. The information obtained from ICP-ASE and CLSM analysis suggested to inhibit growth of O. Xoccosum, the MBT concentration needs to be >55 g/g of dry wood. Due to its high detection capacity, ICP-ASE is identiWed as an excellent tool for MBT detection and quantiWcation in wood.

Chemical Components of Fungus Comb from Indo-Malayan Termite Macrotermes gilvus Hagen Mound and Its Bioactivity against Wood-Staining Fungi

“…The ethyl acetate, methanol, and distilled-water extracts of the fungus comb were dissolved into 5 mL of 5% dimethyl sulfoxide (DMSO, Sigma Aldrich, St. Louis, MO) solvent to get concentrations of 2%, 4%, and 6% (w/v), while for the n-hexane extract were prepared to get concentrations of 0.3%, 0.4%, and 0.5% due to the lower solubility of this extract in the medium. Metilen bisthyocyanate (MBT) as a wood preservative formulation [32] was dissolved in distilled water to get concentrations of 0.02%, 0.03%, 0.6%, 0.13%, 0.25%, 0.50%, 1%, and 2%, respectively, as positive control solutions. Each extract solution, as well as the positive control solutions, was then passed via syringe through a 0.45 µm Microsolve filter to get sterile extract, which was poured into a glass vial.…”

“…In addition, its bioactivity was similar to 0.5% methylene bis-thiocyanate (MBT), used as a positive control solution (as shown in Figure 5). It is widely known that MBT is an active ingredient in synthetic wood preservatives commercially used for preventing wood-staining fungi in wood industries [32]. The high inhibition rate of fungal growth by MBT compounds at low concentrations is influenced by their antifungal mechanism, by blocking electron transfer in the fungus and preventing oxidation/reduction mechanisms [62].…”