Role of Microorganisms in the Digestion of Lignocellulose by Termites

Photosynthetic fixation of carbon dioxide in our biosphere yields approxi­ mately 136 X lOIS g of dry plant material annually, which represents Earth's most abundant form of biomass (88). Two major constituents of such biomass are cellulose and lignin, and hence this material is often referred to as . lignocellulosic biomass, or simply lignocellulose. Most of the synthesis (about 2/3) occurs in terrestrial ecosystems where it is balanced, or nearly so, by the decomposition/respiration side of the carbon cycle (63). Decom­ position of lignocellulose is carr ied out primarily by microorganisms, chiefly fungi and bacteria. However, augmenting the activities of microbes is an arr ay of soil macro-invertebrates, whose effects may range from simple comminution and dispersion of plant material to actual dissimilation of the structural polymers of lignocellulose (86, 90, 91). Among the most abundant and important of these invertebrates ' are termites, which, with their associated microbial symbionts, dissimilate a significant proportion of the cellulose