Application of C-13 NMR to investigate the transformations and biodegradation of organic materials by wood- and soil-feeding termites, and a coprophagous litter-dwelling dipteran larva

Solid-state C-13 nuclear magnetic resonance Spectroscopy has been used to c haracterize the C in samples of the food (wood), gut contents and faeces fr om the wood-feeding termite, Microcerotermes pawns; soil in the guts and mo und material from the soil-feeding termite, Thoracotermes macrothorax; and the food and faeces from the litter-feeding, coprophagous larvae of the dip teran fly, Bibio marci. Spectra from the wood-feeding termite indicated pre ferential loss of polysaccharide and accumulation of lignin with some modif ication to the O-aromatic-C and methoxyl-C (O-methyl-C) components during p assage through the gut. Spectra for the soil-feeding termite indicated litt le change in the distribution of C-13 between resonances following passage through the gut, except for some evidence of preferential polysaccharide lo ss. Interpretation of the spectra from these organisms was restricted by th e relatively low C content of the soils and mound material, and by the larg e contribution to the NMR spectra from the gut tissue rather than the gut c ontents. Spectra for the litter-feeding dipteran larvae indicated preferent ial feeding on the polysaccharide-rich component of the litter and then ove rall loss of polysaccharide-C and accumulation of both aromatic-C and metho xyl-C in the gut. These changes were greater for the second passage than fo r the first passage through the gut, suggesting that principally mechanical and physical changes occurred initially and that chemical digestion was pr evalent during the second passage.