56 Methanogenesis in the Digestive Tracts of Insects

摘要: Termites, cockroaches, and scarab beetles are the only insects known that emit methane, but they do so in impressive amounts. Methanogenesis occurs enlarged hindgut compartment is fueled by hydrogen reduced one-carbon compounds formed during fermentative breakdown of plant fiber humus. The methanogens typically colonize intestinal surfaces or occur as endosymbionts protists. They fall into three major phylogenetic groups (Methanobacteriales, Methanosarcinales, Methanomicrobiales) form distinct clusters mostly uncultivated archaea often unique to tract insects. oxygen-reducing capacities few available isolates their location microoxic gut periphery indicate at least some species this notoriously oxygen-sensitive group well adapted continuous influx oxygen habitat. Although colonization seems require a predisposition host, possible benefits for insect remain be discovered. high methane emissions termites, together with enormous biomass especially tropical regions, make them significant natural source important greenhouse gas.