Archaeal diversity and community structure in the compartmented gut of highert termites

Abstract

Termites are phylogenetically divided into lower and higher termites (Inward et al., 2007). The higher termites, which constitute three quarter of all known termite species, are represented by only one family Termitidae, which exist in great biomass densities especially in tropical ecosystems (Bignell and Eggleton, 2000). The higher termites show a great diversity in feeding behavior, feeding on plant material at different stages of decomposition, from wood to true soil with the majority being soil feeders (Donovan et al., 2001). Together with cockroaches, millipedes and beetles, termites are among the few terrestrial arthropods known to produce methane (Hackstein and Stumm, 1994). Termites produce significant amounts of methane (Sugimoto et al., 2000), and this is attributed to the presence of members of methanogenic archaea in their hindguts. However, methane emission rates vary between termite taxonomy as well as between species (Shinzato et al., 1992; Brauman et al., 1992; Bignell et al., 1997). Soil-feeding higher termites emit more methane than wood-feeding higher ones, with some wood feeding termites emitting little or no methane (Brauman et al., 1992). Also, among the soil-feeders, members of soil-feeding Termitinae emit more methane than the other soil feeding taxa. Generally higher termites emit more methane than their lower termite counterparts and the reason for these differences has not been very clear. Methanogenic archaea, which are responsible for methane production in termites, have been detected in all termites investigated to date (Purdy, 2007).