Sunday, May 4, 2008
2-07

Lignocellulose biodegradation by wood-feeding termites: Fundamentals and applications

Jianzhong Sun, Coastal Research and Extension Center, Mississippi State University, 810 Hwy. 26 West, P.O. Box 193, Poplarville, MS 39470

Termites are among the most important and effective lignocellulose-digesting invertebrates on the earth. As the world’s smallest bioreactors, the degradation of wood by termites is very unique and highly efficient, which demonstrates combined actions of the termite and its hindgut microbial symbionts in the utilization of 74-99% of the cellulose and 65-87% of the hemicellulose, as well as 2-83% lignin of the ingested plant material. Two main contributions of the termite to the breakdown of lignocellulose are the provision of small wood particles and the excretion of endogenous cellulases or hemicellulases. The utilized wood is grinded by termite mandibles to particles < 50 µm in size that would increase the surface area and, therefore, the accessibility to hydrolyzing enzymes. In lower termites, wood particles are endocytosed by the archaezoa. The passage of the wood particles through the digestive tract of a wood-feeding termite only takes < 24 h, which is a more efficient bioconversion in degrading lignocellulose than wood-rotten fungi. Cellulose and hemicellulose related enzyme systems are identified either from the termite or from its gut symbionts. The symbiosis between termites and the gut flora can be described as a synergistic interaction of termite and microbial origin enzymes. Sequencing work on termite or its symbionts’ genes associated with cellulolytic activities has already shown a promising future. In this presentation, an outlook is made for the present progress in understanding termite digestive systems and particularly how we can possibly, with research on wood-feeding termites, harness the pathways towards biofuel applications.

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