Cellulase Activity in Higher and Lower Wood-Feeding Termites

Abstract

Wood-feeding termites have evolved efficient cellulose-decomposing systems. The cellulase activity and distribution of workers were studied in three wood-feeding termites from phylogenetically different lineages; the lower termites, Crypototermes domesticus (Haviland) (Isoptera: Kalotermitidae) and Coptotermes formosanus Skiraki (Rhinotermitidae), and the higher termite, Ahmaditermes sichuanensis Xia et al. (Termitidae). The results showed that the total cellulase activity of the higher termite A. sichuanensis was markedly higher than that of the lower termites. Co. formosanus had the highest activity of endo-β-1,4-glucanase and cellobiohydrolase. The activity of β-glucosidase was not significantly different among the three species. The proportion of cellobiohydrolase was higher in the higher termite. In terms of distributions of cellulolytic activity in the gut, the primary site of endo-β-1,4-glucanase activity was presented in the hindgut of both the lower termites but in the midgut of the higher termite, and the primary site of β-glucosidase activity was restricted to the midgut in the lower termites and the head/foregut in the higher termite. The functions of the gut segments were apparently differentiated between the lower and higher termites, with the role of the midgut becoming more important in the higher termite. For the endogenous cellulases, the main site of endo-β-1,4-glucanase activity was concentrated in the midgut in both the lower termite and the higher termite, but the main site of β-glucosidase activity was in the head/foregut in the higher termite. The results suggest that characters of cellulase activity could reflect the phylogenyof wood-feeding termites to a certain extent.