Energy Metabolism in the Termite and Its Gut Microbiota

Abstract

The major source of energy in all termites is carbohydrate although the nature of the carbohydrate is known only in the xylophagous termites. Lignin degradation does not appear to be important in any group of termites. All termites examined secrete their own cellulases. The site of secretion in the lower termites is the salivary glands and in the higher termites, the midgut epithelium. Lower termites harbour cellulolytic protists as do some of the higher termites. Cellulolytic bacteria are not of major importance. The major substrates used by the termite are glucose derived from cellulose breakdown and acetate derived from fermentation in the hindgut. Both aerobic and anaerobic metabolism occur in the gut. While the substrates for bacterial fermentation are largely a matter for speculation, the principal end products are acetate and CO2 with CH4 and H2 being the minor end products. Nitrogen fixation in the hindgut is significant in many termites and is a major role for the symbiotic bacteria.