Degradation of aromatic compounds by Scedosporium species

Scedosporium are saprophyte fungi and human opportunistic pathogen. Natural niches and reservoirs of these species are potential sources of human contamination. Firstly, we studied the distribution of the different Scedosporium species in the regions of two large cities of Morocco (Rabat-Sale Kenitra and Fez-Meknes). Our results demonstrated a predominance of S. apiospermum (56%), followed by S. boydii (18%), S. aurantiacum (17%) and S. dehoogii (9%). Considering physico-chemical parameters of samples, these species preferred a soil with neutral pH (7.0-7.6), rich in nutrients and exhibing a phosphorus content between 200-300 ppm. As previously reported, these fungi were mainly found in anthropized environments. Various studies suggest a link between the fungal adaptation to polluted environments and their lignolytic abilities. We evidenced that Scedosporium species were able to grow using the lignocellulose components as carbon source. Bioinformatic analysis correlated with enzymatic assays and analysis of relative gene expression by RT-qPCR suggested the involvement of four peroxidases and five oxidases in lignin destructuration by Scedosporium species. In nature, extracellular oxidative degradation and the following steps of lignin degradation channeled into few monocyclic conserved intermediates: catechol, protocatechuate, hydroxyquinol and gentisate. Identification of ring-cleavage dioxygenases in Scedosporium genome highlighted cluster organization of the main catabolism pathways of aromatic compounds. Finally, experimental results demonstrated the induction of gentisate cluster genes in the presence of this last molecule and lignin.