The Distribution and Origins of the Cellulolytic Enzymes of the Higher Termite, Macrotermes natalensis

Publisher Website
Google Scholar
Abstract
All of the enzymes required for the digestion of native cellulose, as well as of xylan and pectin, are present in the gut fluids of adult workers of the fungus-growing termite, Macrotermes natalensis. Activity levels are highest in the midgut, suggesting that this portion of the gut, rather than the paunch, is the major site of polysaccharide digestion in this higher termite. The Ci-enzymes, active against crystalline cellulose, are acquired by the termites when they feed upon the fungus nodules which grow on their fungus combs. The -enzymes, active against noncrystalline cellulose and soluble derivatives and degradation products of cellulose, are derived in part from ingested fungal material, and in part they are produced internally by the termite, being secreted both by the midgut epithelium and the salivary glands. The nutritional dependence of the termites on their fungus gardens is explained in terms of their reliance upon the fungus nodules as a source of the critical C₁-enzymes, which must be acquired before they are able to effect the digestion of cellulosic materials. It is proposed that a strategy of resource utilization based upon the acquisition of digestive enzymes which expand the range of natural substrates suitable for exploitation as nutrient sources may be a general one.