Impact of lignin depolymerization on aerobic and anaerobic bioconversion of alkaline liquor from sugarcane bagasse.

Introduction: Lignin recalcitrance, together with its complex interactions with cellulose and hemicelluloses within the plant cell wall, remains a major barrier to efficient lignocellulosic biomass valorization. Mild alkaline pretreatment partially addresses this challenge by solubilizing lignin and acetate into a lignin-rich alkaline liquor (AL). However, the recovered lignin is largely oligomeric, limiting its direct microbial conversion. Methods: To evaluate strategies for improving AL bioconversion, alkaline liquor was subjected to thermochemical depolymerization under different severities, generating liquors with compositions ranging from oligomer-rich to monomer-rich profiles. The resulting streams were evaluated through two bioconversion routes: aerobic metabolism by Results: Mild to moderate depolymerization conditions (≤240 °C) improved the growth of Discussion: These findings demonstrate that controlled lignin depolymerization can enhance both aerobic and anaerobic bioconversion by balancing chemical accessibility with biological compatibility. This approach provides a promising strategy for improving lignin utilization within integrated biorefinery concepts.