The Route of Lignin Biodegradation for Its Valorization

Using lignin to produce high-value-added aromatic fine chemicals and high-grade biofuels such as aromatics, cycloalkanes, and alkanes can reduce the dependence on fossil resources and highly improve the competitiveness of biorefining industry. The biological valorization of lignin includes the biological depolymerization and bioconversion of lignin. With the development of bioprospecting and systems biology technology, more and more lignin-degrading microorganisms have been discovered and separated from the natural habitat of lignin decomposition. The physiological and biochemical characteristics of microorganisms and the molecular- and systematic-level degradation mechanism on lignin and lignin-derived aromatic compounds have also been deeply recognized. All of these have laid a theoretical foundation for precisely controlling the depolymerization and metabolism of lignin and establishing the biological processing pathway of lignin. This chapter will introduce the research progress of lignin valorization from the aspects of lignin-degrading microorganisms and enzymes, lignin degradation metabolic pathways, and the application of biosynthesis in lignin conversion.