Changes of EPR spectra of wood, impregnated with copper based preservatives, during exposure to Antrodia vaillantii
M Humar, M Petric, F Pohleven, M Šentjurc
Spruce wood (Picea abies) samples were impregnated with two different aqueous solutions: copper(II) octanoate with ethanolamine or copper(II) sulfate (cCu = 1,0 x 10-2 mol/l). Impregnated and unimpregnated test pieces were exposed to wood rotting fungus Antrodia vaillantii. Some strains of this fungus are known as copper tolerant. After four weeks of exposure to A. vaillantii, we could not detect any Electron Paramagnetic Resonance (EPR) signal of Cu(II) in the spectrum of copper(II) sulfate treated wood. This means that Cu(II) was translocated or conversed into a form that cannot be detected by EPR. Instead of copper signal, manganese signal appeared. The same, manganese signal appeared also in untreated wood, after exposure to A. vaillantii. On the other hand, line shapes of the EPR spectra of Cu(II) in copper(II) octanoate/ethanolamine treated wood changed by rotting, from anisotropic to isotropic. We believe that these changes are mostly caused by oxalic acid, excreted by A. vaillantii, because we observed the same changes on EPR spectra of impregnated and unimpregnated wood, additionally treated with oxalic acid.