Lignocellulolytic enzymes from tropical fungi: Types, substrates and applications

Abstract

Lignocellulolytic enzymes constitute a large group of mainly extracellular proteins including ligninolytic enzymes (peroxidases and oxidases) and hydrolytic enzymes (cellulases, hemicellulases, pectinases, chitinases, amylases, proteases, esterases, and mannases). These enzymes have attracted a wide range of industrial and environmental applications including pulping, de-inking, decolourization and detoxification of textile wastes, wastewater treatment and bioremediation of polluted soils. This work gives an updated review and summarizes the main fungal strains, substrates, lignocellulosic enzymes and their applications with an emphasis on tropical fungi. The main groups of lignocellulolytic enzymes and their applications are summarized in a manner that provides a useful reference for both enzyme scientists and technologists. Moreover, current debates and significant gaps in the lignocellulolytic fungal enzymes’ research have been highlighted. Future prospects in lignocellulolytic enzymes research are directed towards bioprospecting of robust novel fungal enzymes to overcome the challenge of recalcitrant substrates, physiological regulations of enzymes, use of novel inducers to enhance production, use of multiple fungal strains or mixture of enzymes, gene cloning to screen for new generation of enzymes and nanobiotechnologal applications in enzymology. This review revealed that for the past seven years, lignocellulolytic enzymes research and development have been steadily advancing from cellular to molecular; and from micro- to nano- levels, and more efforts should be directed to new research frontiers including molecular cloning, sequencing and functional genomics. Key words: Biodegradation, lignocellulolytic enzymes activities, liquid culture, nanobiotechnology, solid state fermentation.