Lignin depolymerization and biotransformation to industrially important chemicals/biofuels

Lignin is a potential feedstock due to its energy content and its abundant availability from biomass based biorefinery. Among the different fractions of biomass, lignin has been under utilized due to its hetero aromatic polymeric structure. Development of options for lignin or lignin rich residue valorization can balance the economics of bioethanol based biorefineries. Lignin is also being viewed as alternative to the aromatics and polymer industry, apart from the source of biofuels/bioenergy. In spite of various physico-chemical and other available abiotic methods, biological methods of lignin depolymerization and its transformation to biofuels or value-added products got significance due to their economic and environmentally benign nature. Extensive research has been carried out on the biological methods of lignin depolymerization, considering fungi, enzymes and bacteria. In this review, a comprehensive view on types of lignin and their characteristics, existing methods of lignin depolymerization with a special emphasis on microbial methods and various industrial applications, viz., biofuels, lipids, polyhydroxyalkanoates, vanillin and dicarboxylic acid, etc., were presented. In conclusion, the critical aspects of lignin depolymerization to be considered to increase the product yield and possible future perspectives were also discussed.

Automated summary

Lignin, as a potential feedstock in biomass based biorefinery, can be depolymerized and transformed into biofuels or high value-added products using biological methods, which have economic and environmentally friendly advantages.