DIGESTION OF LIGNIN BY TERMITES

The termite Nasutitermes exitiosus (Hill) was fed natural and synthetic [14C]labelled lignins and related compounds, and the respired CO2 collected. All the compounds were partially degraded to CO2, from an average of 7% of the added 14C for ring-labelled phenate to 63% for methoxyl-labelled maize lignin and 64% for ring-labelled ferulic acid, during periods of 6-69 days. The breakdown commenced immediately and was linear until the food was consumed. Thereafter a slow release continued for some time. Termite bodies assayed at the end of the experiments contained only a small proportion of the added radioactivity. When live termites were separated from their faeces, it became apparent that most of the decomposition of lignin had taken place in the termites and not externally in the voided faeces. An estimate of respiration rates of N. exitiosus indicates a significant release of C as respired CO2, and this species of termite would appear to return a considerable proportion of the C in litter lignin directly to the atmosphere. © 1979.