A feasible role of sulfate-reducing bacteria in the termite gut

Sulfate-reducing bacteria were isolated from termites belonging to different families of lower and higher termites. In the presence of sulfate rich diet up to 10(8) sulfate-reducers per ml paunch content were counted in the case of Reticulitermes santonensis. All isolates were assigned to the genus Desulfovibrio and are closely related to Desulfovibrio desulfuricans or Desulfovibrio termitidis because of their physiological and biochemical features as well as their 16S rDNA sequence. The isolates oxidized H-2, lactate, formate, ethanol and even reduced sulfur compounds such as sulfide, thiosulfate or sulfite with oxygen. High respiration rates (1570 nmol O-2 min(-1) mg protein(-1)) were obtained with H-2 at low oxygen concentrations. This survey shows that desulfovibrios are widespread among termites and that they may fulfill several important functions in the ecosystem ''termite gut''.