Constructing metabolic pathway of lignin monomers and their derivatives based on metabolic recombination models and...

Lignin stands as the second most abundant biopolymer in the world; however, its valorization is hindered by its complicated recalcitrant structure. Beyond the challenge of depolymerization, the phenolic intermediates resulting from the depolymerization process are also recalcitrant to degradation by the majority of microorganisms. To deeply understand the biodegradation pathways of lignin, a comprehensive biochemical metabolism network is constructed, amalgamating all relevant biochemical reactions, compounds, and enzymes in KEGG database. This network forms the foundation for metabolic recombination models, which facilitates computing the rearrangement and combination processes across various metabolic pathways. Utilizing these metabolic recombination models, multiple pathways were computed that enable the degradation and transformation of lignin monomers and their derivatives into acetyl CoA. The thermodynamic viability and theoretical yield of these diverse degradation pathways are investigated, employing the yield model based on the computational results of the recombination pathways. These results underscore the potential of metabolic recombination models to broaden the scope of lignin biodegradation strategies and to meticulously design biodegradation pathways tailored for refractory pollutants. This approach not only advances understanding of lignin degradation but also provides a theoretical basis for biodegradation of refractory pollutants.