Wood-Rotting Fungi for Biofuel Production

Abstract

Lignocellulosic biomass (forest biomass and wastes, agricultural residues, and energy crops) have been focused on as potential materials for the second-generation bioethanol production because of their beneficial characteristics, including renewability, high annual yield, abundance, etc. Wood-rotting basidiomycetes play an important role in the carbon cycle as decomposers in forest ecosystems. Among these fungi, white-rot fungi are the only microbes capable of efficient depolymerization, degradation, and mineralization of all the components of lignocellulosic materials. Especially, white-rot fungi can degrade and remove lignin via the production of a diverse range of oxidizing enzymes, such as manganese peroxidase, lignin peroxidase, and versatile peroxidase. The enhancement of saccharification rate by wood-rotting fungi pretreatment has been widely reported. Different white-rot and brown-rot fungi genera, such as Phlebia, Pleurotus, Ceriporiopsis, Flammulina, Trametes, Irpex, Peniophora, Echinodontium, Punctularia, Cyathus, Daedalea, Schizophyllum, Lentinula, Ganoderma, Gloeophyllum, and Fomitopsis, have shown high potentials in the processes of bioethanol production. In this chapter, the applications of these fungi in biological pretreatment for lignocelluloses, direct fermentation of lignocellulosic materials to ethanol through consolidated bioprocessing (CBP) fermentation, and integrated fungal fermentation process (IFFP) are discussed. Finally, recent achievements in the field of metabolic engineering of white-rot fungi to enhance pretreatment efficiency and ethanol yield and to change the metabolic products are presented.