Uncovering the intrinsic lignin-metabolizing machinery of Myceliophthora thermophila for integrated lignocellulose valorization

Specifically, we identified that M. thermophila funnels diverse p-hydroxyphenyl (H) and guaiacyl (G) aromatic monomers into the 3,4-dihydroxybenzoic acid (protocatechuic acid, 3,4-DHB) branch of the β-ketoadipate pathway. Importantly, disruption of the protocatechuate hydroxylase and 3,4-dioxygenase genes successfully redirected metabolic flux, enabling efficient bioconversion of H- and G- type monomers into 3,4-DHB with molar yields ranging from 42.5% to 95.8%.

Moreover, the engineered strains achieved direct production of 3,4-DHB from raw corncob. These findings reveal the intrinsic lignin-assimilating machinery of M. thermophila and establish a critical foundation for integrated lignocellulose biorefineries and aromatic bioprocessing.