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

KOCH, E.; LOZADA, M.; DIONISI, HM.; CASTRO-VAZQUEZ, A.

Mendoza

Congreso; XXVII Reunión Anual de la Sociedad de Biología de Cuyo; 2011

Sociedad de Biología de Cuyo

Uric acid degradation by gut bacteria in the apple-snail Pomacea canaliculata Koch E, Lozada M, Dionisi HM, Castro Vazquez A. Instituto de Ciencias Básicas, UNCuyo, CENPAT-CONICET (Puerto Madryn) and IHEM_CONICET, Mendoza. E-mail: ekoch@uncu.edu.ar In previous publications we studied uric acid deposits in specialized tissues from Pomacea canaliculata, which may play an important role in their nitrogen metabolism. The re-utilization of combined nitrogen for the synthesis of amino acids and the nitrogen base moieties of nucleic acids requires the previous degradation of uric acid to ammonia. The first step of this pathway is the oxidation of uric acid to allantoin by uricase (=urate oxidase, EC 1.7.3.3). We found that this animal bears intestinal bacteria with the capacity of growing in a selective medium that contains uric acid as the only carbon and nitrogen source, so that they should be able to degrade this purine. A total of 8 bacterial strains able to grow in the selective medium were first distinguished on the basis of colony type and Gram staining: 7 Gram(-) bacilli and 1 Gram(+) coccus. DNA extracts from the Gram(-) strains were used as templates for the PCR amplification of the ribosomal RNA 16S gene. The amplified products were sequenced and compared with GenBank data, indicating the occurrence of Enterobacter, Pseudomonas and Citrobacter as uric acid degrading bacteria. Provisionally, the uric acid degrading Gram(+) coccus was biochemically identified as Enterococcus faecium. Results indicate that several gut bacteria may participate in uric acid recycling in this snail.