CHAPTER 11: Lignocellulolytic Systems of Insects and their Potential for Viable Biofuels

Lignocellulose digestion has demonstrated in some herbivorous, xylophagous, and even some aquatic foliage- and detritus-feeding insects that are phylogenetically divided into more than 20 families representing ten distinct insect orders, e.g. Thysanura, Plecoptera, Dictyoptera, Orthoptera, Isoptera, Coleoptera, Trichoptera, Hymenoptera, Phasmida, and Diptera. However, a difference in their ability to deconstruct lignocellulosic biomass is virtually significant due to various lignocellulolytic systems evolved by these cellulose-feeding insects. This chapter examines some representative cellulose-feeding insects, especially wood-feeding termites and their three unique lignocellulolytic systems that accomplish lignocellulose digestion using specialized gut physiology, endogenously produced digestive enzymes, and via their specialized association with prokaryotic and eukaryotic gut symbionts. In recent years, exploring insect lignocellulolytic systems stimulated by the interest in biofuels have led to discover a variety of novel biocatalysts/encoding genes, as well as the associated unique mechanisms for efficient biomass conversion. Thus, more evidence has been accumulated via these investigations that the bioconversion technologies of lignocellulosic biomass to various fuels and chemicals could be significantly improved and optimized by applying the nature-inspired strategy and technology explored from insect lignocellulolytic systems.