A cellulase gene of termite origin

The traditional view of cellulose digestion in animals is that they cannot produce their own cellulase, and so rely on gut microorganisms to hydrolyse cellulose. A classic example of this symbiosis is that between phylogenetically lower termites and the unicellular organisms (protists) that colonize their hindguts: cellulose fermented to acetate by the protists can be used as an energy source by the termite1. There is evidence for the production of endogenous cellulase components by termites and other wood-feeding insects2; however, an unambiguous origin for such enzymes1 has not been established, to our knowledge, until now. Here we describe the first insect cellulase-endoding gene to be identified, RsEG, which encodes an endo-β-1,4-glucanase (EC 3.2.1.4) in the termite Reticulitermes speratus.