Comparative diversity of NarG gene in the Suquía River Sediments.

REYNA, L.; WUNDERLIN, D.A.; GENTI-RAMONDI, S.

Carlos Paz

Congreso; REUNIÓN SAIB 2008; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.

We report the molecular characterization of narG gene in sediments isolated from two distant sites of the Suquía River of Córdoba Province, where different nitrate concentrations were observed. This analysis was performed using narG RFLP, cloning and sequencing. A total of 195 narG clones of two libraries were screened. Among 51 RFLP patterns identified, only one was found in both sediments. Rarefaction curves of the amino acid sequences predicted a greater diversity from the narG genes obtained in the sediment where the higher freshwater nitrate levels were found. Ninety different sequences were obtained and the identities between the deduced amino-acid sequences and those from cultivated or environmental denitrifier bacteria deposited in the databases ranges from 57-100%. Phylogenetic analysis grouped the 195 narG clones  in seven clusters related to the b-proteobacteria (33%), aproteobacteria  (30%), d-proteobacteria (3%), g-proteobacteria (2%) and Thermus thermophilus (10%) narG genes. The rest of the clones were less than 68% similar to narG sequences available in databases suggesting that they are indigenous of the Suquía River. The results indicate that the nitrate reducing communities present in the Suquía River sediments are phylogenetically diverse and divergent from previously descripted sequences. were less than 68% similar to narG sequences available in databases suggesting that they are indigenous of the Suquía River. The results indicate that the nitrate reducing communities present in the Suquía River sediments are phylogenetically diverse and divergent from previously descripted sequences. were less than 68% similar to narG sequences available in databases suggesting that they are indigenous of the Suquía River suggesting that they are indigenous of the Suquía River.