# FTIR Spectroscopy for Identification and Intra-Species Characterization of _Serpula Iacrymans_
## 4 Discussion  
The treatment of fungal growth in a building begins with identifying and eliminating the source of the moisture to stop the growth [1]. Then, it is necessary to determine the extent of the damage by inspecting all areas of the building where the fungus may have spread [7]. This also helps to characterise the type of wood decay (brown rot, white rot, and/or soft rot) and guide the identification of the fungi involved. This identification is essential as the course of action will depend on whether or not _S. lacrymans_ is present. If _S. lacrymans_ is not involved, the damage is minor and the fungal growth is limited to the areas where the wood is degraded. Therefore, treatment can be limited to allowing the building to dry out by ventilating it. However, if the source of the moisture cannot be removed immediately or the building cannot be allowed to dry out, fungicidal treatments  
Figure 4: Confusion matrix obtained for the discrimination of the strains after growth on the PES membrane, and direct analysis on the membrane. Min-max normalization (**A**), Vector normalization (**B**). _R. p., Rhodonia placenta. S. l., Serpula lacrymans. T. h., Trichoderma hurzainum._  
Figure 5: Confusion matrix obtained for the discrimination of the strains after growth in liquid medium. Min-max normalization (**A**), or Vector normalization (**B**). _R. p., Rhodonia placenta. S. l., Serpula lacrymans. T. h., Trichoderma harzainum._  
are applied and the contaminated woodwork and plasterwork is destroyed. In the case of _S. lacrymans_, uncontaminated woodwork adjacent to areas where the fungus is present is also destroyed. Furthermore, in France, the occupant or owner of the building affected by _S. lacrymans_ has a legal obligation to declare the presence of the fungus in the building to the city hall [28]. In the case of a historic building which may have valuable woodwork and walls decorated with sculptures or paintings, care should be taken and biocidal treatments with the least possible impact on the materials should be used. In this context, the identification of _S. lacrymans_ in the early stages is essential. The identification of fungi involved in wood biodegradation through culture and molecular methods could be tedious, time-consuming and/or expensive. FTIR spectroscopy has shown its suitability for the identification of fungi of medical or food interest, but few data exist for wood-rot fungi [19; 22; 27; 29]. This identification method is based on the global analysis of the mycelium or spores of a fungus to determine its spectral profile and to compare it to reference spectra [19; 20]. The IR spectrum obtained for a fungus corresponds to all the biomolecules present in the biomass at the time of analysis. The differences in the composition and quantity of these biomolecules between species, genera or strains make it possible to differentiate fungi by FTIR spectroscopy. These parameters vary for the same individual depending on the stage and conditions of growth [30]. In this study, the application of FTIR spectroscopy to the identification and discrimination of _S. lacrymans_ strains was evaluated. Reference FTIR spectra were made from different strains of _S. lacrymans_, _R. placenta_ and _T. harzianum_ after growth under standardised conditions. The analysis was carried out using a wide spectral range extending from 3700 to 2800 and from 1800 to 600 cm\({}^{-1}\), which corresponded to the signals obtained for the main biological macromolecules carbohydrates, proteins, lipids and nucleic acids [16; 19; 31]. The analysis of FTIR spectra was completed from fungal mycelium and not from fungal spores in order to obtain more complex spectra and a better discrimination [19; 20; 22; 23]. Furthermore, _R. placenta_ and _S. lacrymans_ did not sporulate under the laboratory conditions used. Several culture protocols have been described for FTIR application.