Uric acid degradation by gut bacteria in the apple-snail Pomacea canaliculata

KOCH, E; LOZADA, M.; DIONISI, H.; CASTRO VAZQUEZ, A.

Ciudad de Mendoza, Argentina

Congreso; XXVIII Annual Scientific Meeting Cuyo Biology Society; 2010

Cuyo Biology Society

In previous publications we studied uric acid deposits in specializedtissues from Pomacea canaliculata, which may play an importantrole in their nitrogen metabolism. The re-utilization of combinednitrogen for the synthesis of amino acids and the nitrogenbase moieties of nucleic acids requires the previous degradation ofuric acid to ammonia. The first step of this pathway is the oxidationof uric acid to allantoin by uricase (=urate oxidase, EC 1.7.3.3).We found that this animal bears intestinal bacteria with the capacityof growing in a selective medium that contains uric acid as theonly carbon and nitrogen source, so that they should be able todegrade this purine. A total of 8 bacterial strains able to grow in theselective medium were first distinguished on the basis of colonytype and Gram staining: 7 Gram(-) bacilli and 1 Gram(+) coccus. DNAextracts from the Gram(-) strains were used as templates for thePCR amplification of the ribosomal RNA 16S gene. The amplifiedproducts were sequenced and compared with GenBank data, indicatingthe occurrence of Enterobacter, Pseudomonas andCitrobacter as uric acid degrading bacteria. Provisionally, the uricacid degrading Gram(+) coccus was biochemically identified asEnterococcus faecium. Results indicate that several gut bacteriamay participate in uric acid recycling in this snail.