White rot fungi (WRF) are the most efficient organisms for the depolymerization and mineralization of lignin to CO2 and H2O in Nature and thus, WRF play a pivotal role in carbon cycling. Lignin depolymerization by WRF (extracellular process) has been studied for decades. However, almost no attention has been dedicated to the elucidation of the intracellular metabolism of WRF in catabolizing lignin. Thus, we propose to elucidate new metabolic pathways in WRF involved in the catabolism of lignin-derived aromatic compounds. For this purpose, we will the need support from EMSL's advanced multi-omics capabilities (transcriptomics, proteomics, and metabolomics) while subjecting two fungi - reported to depolymerize lignin efficiently - to diverse substrates such as glucose, cellobiose, aromatic compounds, and poplar in different cellular loci and redox states. In addition, at NREL, we will characterize the lignin after the fungal treatments and will perform genomic and carbon flux studies by using 13C labeled aromatic compounds and poplar. Understanding how and where WRF mineralize aromatic compounds will not only be valuable steps toward a deeper insight into global carbon cycling and soil ecosystems science, but will also serve to develop new hosts for further metabolic engineering and produce high-value coproducts from lignin. Taken together, this work could lead to legacy, novel, and high impact science.