Uric Acid-Degrading Bacteria in Guts of Termites [Reticulitermes flavipes (Kollar)]

Uricolytic bacteria were present in guts of Reticulitermes flavipes in populations up to 6 × 10⁴ cells per gut. Of 82 strains isolated under strict anaerobic conditions, most were group N Streptococcus sp., Bacteroides termitidis, and Citrobacter sp. All isolates used uric acid (UA) as an energy source anaerobically, but not aerobically, and NH₃ was the major nitrogenous product of uricolysis. However, none of the isolates had an absolute requirement for UA. Utilization of heterocyclic compounds other than UA was limited. Fresh termite gut contents also degraded UA anaerobically, as measured by ¹⁴CO₂ evolution from [2-¹⁴C]UA. The magnitude of anaerobic uricolysis [0.67 pmol of UA catabolized/(gut × h)] was entirely consistent with the population density of uricolytic bacteria in situ. Uricolytic gut bacteria may convert UA in situ to products usable by termites for carbon, nitrogen, energy, or all three. This possibility is consistent with the fact that R. flavipes termites from UA, but they do not void the purine in excreta despite the lack of uricase in their tissues.