Hydrogen emission by three wood-feeding subterranean termite species (Isoptera: Rhinotermitidae): Production and characteristics

Hydrogen emission by wood-feeding termites, Coptotermes formosanus, Reticulitermes flavipes and Reticulitermes virginicus, was investigated upon a cellulosic substrate as their food source. The emission rates among the three species tested were significantly different and R. virginicus demonstrated the greatest H(2) emission at 4.78 +/- 0.15 mu mol/h/g body weight. In a sealed test apparatus, H(2) emission for each termite species showed a quick increase at the initial incubation hours (3-6 h), followed by a slower growth, possibly due to the feedback inhibition by gas accumulation. Further investigation revealed that continuous H(2) emission could be maintained by reducing the H(2) partial pressure in the sealed container. The bioconversion of cellulose to molecular H(2) by the subterranean termites tested could reach as high as 3 858 +/- 294 mu mol/g cellulose, suggesting that the termite gut system is unique and efficient in H(2) conversion from cellulosic substrate.