THE ROLE OF THE SYMBIOTIC FUNGUS IN THE DIGESTIVE METABOLISM OF SEVERAL SPECIES OF FUNGUS-GROWING TERMITES

1. The comparative study of digestive osidases in five fungus-growing species and its symbiotic fungus (Termitomyces sp.) brings new insight into the nutritive mode of these species, known to have a great impact in most African ecosystems. 2. While this work stressed the importance and the variety of enzymatic activities detected in the termite workers digestive tract, our results clearly distinguished two main symbiotic mechanisms into termite nutrition, according to the ability for the symbiotic fungus to produce active enzymes. 3. In the case of Macrotermes bellicosus, Odontotermes near pauperans and Pseudacanthotermes militaris, the metabolism of the fungi is characterized by a relatively higher enzymatic production (variable according to the substrates tested). 4. These enzymes are ingested by the termite and the digestion is due to the combined action of the enzymes from the termite gut and from the fungus. 5. In the case of Ancistrotermes cavithorax and Microtermes toumodiensis, one can question the role of the fungi as they exhibited very low enzymatic activities. 6. The fungus protoplasm could then be a nutrition source for the termite. Possibly also, these fungi could degrade other substrates (chitin, lignin) not tested in our experiments. 7. Our results showed also a very high oligosaccharidasic activity of Pseudacanthotermes militaris symbiotic fungus (Termitomyces striatus) which appear to coincide with a different behaviour of the termite towards its fungus comb.