ISEN METAGENOMIC DISCOVERY OF NOVEL LIGNIN - DEGRADING FUNGI FOR BIOFUEL PRODUCTION Louise

BACKGROUND AND OBJECTIVES The bio-conversion of plant lignocellulose to glucose is an key component of second generation biofuel production, but the resistance of lignin to breakdown is a major obstacle in this process. Filamentous fungi possess the unique ability to decompose the aromatic lignin polymers using enzymes encoded by divergent gene families. White-rot fungi are the primary lignin-degraders, and produce phenol oxidases (laccase) or heme peroxidases (lignin, manganese, versatile peroxidases) to completely mineralize lignin and expose the cellulose in the matrix. Brown rots and soft-rots modify the lignin structure and facilitate the access of enzymes produced by white rots. Nevertheless, few fungi are used as pre-treatments for improved bioconversion. In fact, only three species of wood-rotting fungi, most notably Trichoderma, are used to depolymerize plant biomass to simple sugars that, in turn, are converted to chemical intermediates and biofuels. Outside of Trichoderma, the process of lignin degradation by other types of fungi is largely unknown, and only partial lignin depolymerization and modification have been documented in bacteria.