Biological valorization strategies for converting lignin into fuels and chemicals

Lignin is a complex phenylpropanoid biopolymer conferring mechanical strength to plant cell walls. Biorefineries, along with pulp and paper industry, generate large quantities of lignin. Lignin valorization is an essential process for an advanced, sustainable, and economical biomass-based industry. However, converting lignin into value-added products remains a challenge due to its heterogeneity and irregular structure. Many wild microorganisms have evolved complex metabolic and enzyme systems for lignin degradation and conversion. Great efforts have been made to explore their potentials for lignin valorization. This paper reviews the recent development in biological conversion of lignin into value-added products. It also covers potential catabolic pathways, exploration of new lignin degradation systems, and lignin consolidated bioprocessing (Lignin CBP).