Introduction: The widespread use of low-durability wood species has led to the adoption of impregnation agents with broad-spectrum biocidal properties. One such agent, Tanalith-E3474, contains copper carbonate and two triazoles (tebuconazole and propiconazole). Due to their toxicity, treated wood cannot be easily recycled. However, certain microorganisms can degrade or sequester these compounds, offering promising avenues for bioremediation. Previous work from our group identified wood-decaying fungi as strong candidates.

Materials and Methods: We established microcosms containing Phanerochaete chrysosporium (white-rot) or Rhodonia placenta (brown-rot), along with a consortium of 10 bacterial species from the Burkholderia, Dyella, and Paraburkholderia genera. The solid phase consisted of pine sawdust impregnated with Tanalith, and the liquid phase was malt extract. Microcosms were incubated at 28°C for 10 days. Triazole concentrations in both phases were quantified by LC-MS using SIM or MRM modes. LC-MS/MS with data-dependent acquisition (DDA) was used to analyze xenobiotic by-products in the liquid phase.

Results: Only R. placenta was able to leach tebuconazole and propiconazole from the solid phase, but it could not degrade them without bacteria. In contrast, P. chrysosporium degraded both compounds, reducing their concentrations by 50% within 10 days. The addition of the bacterial consortium accelerated this process by a factor of ten. Molecular networking and CID-based fragmentation analysis enabled the annotation of 13 by-products and the proposal of a biodegradation pathway.

Conclusion: We demonstrate that fungal-bacterial consortia enhance triazole degradation in treated wood. P. chrysosporium alone degrades these compounds, but co-cultivation with bacteria significantly improves efficiency. Moreover, fungal- and bacteria-mediated degradation pathways appear to be complementary. Further work is needed to identify the specific bacterial species involved. This is the first report using molecular networks to characterize triazole by-products, and our approach may be extended to screen other xenobiotic-degrading organisms.