Microbial lignin peroxidases: Applications, production challenges and future perspectives

Lignin serves as the most abundant source of aromatic high-value products, but it has remained underexploited due to its inert and recalcitrant nature. White-rot basidiomycetes degrade lignin by secreting a set of lignin-modifying enzymes, including lignin peroxidase (LiP), manganese peroxidase, versatile peroxidase, laccase and various auxiliary enzymes. Among these, LiP presents significant potential for application in various industrial sectors such as second-generation biofuels, cosmetics, food, bio-pulping and biobleaching. However, the lack of commercial LiP preparations has hindered its industrial application. In addition, they are unstable at high temperatures, deactivated by solvents, susceptible to inactivation by hydrogen peroxide and challenging to produce in ample quantities. Several expression systems have been investigated to produce LiP, with fungal hosts that have shown the most promise to date. We discuss the progress and challenges of producing native and recombinant LiPs, and offer some future prospects on strategies to enhance the recombinant production of LiPs for industrial and biotechnological applications.